Chapter VI: ARCHITECTURE, ART, ETC.--Artist's Homes. No. 11. "Weirleigh." (4)

III. _Transmission by Pressure Water_.--As transmission of power by compressed air has been specially applied to the driving of tunnels, so transmission by pressure water has been specially resorted to for lifting heavy loads, or for work of a similar nature, such as the operations connected with the manufacture of Bessemer steel or of cast-iron pipes. The author does not propose to treat of transmissions established for this special purpose, and depending on the use of accumulators at high pressure, as he has no fresh matter to impart on this subject, and as he believes that the remarkable invention of Sir William Armstrong was described for the first time, in the "Proceedings of the Institution of Mechanical Engineers." His object is to refer to transmissions applicable to general purposes.

The transmission of power by water may occur in another form. The motive force to be transmitted may be employed for working pumps which raise the water, not to a fictitious height in an accumulator, but to a real height in a reservoir, with a channel from this reservoir to distribute the water so raised among several motors arranged for utilizing the pressure. The author is not aware that works have been carried out for this purpose. However, in many towns a part of the water from the public mains serves to supply small motors--consequently, if the water, instead of being brought by a natural fall, has been previously lifted artificially, it might be said that a transmission of power is here grafted on to the ordinary distribution of water.

Unless a positive or negative force of gravity is introduced into the problem, independently of the force to be transmitted, the receivers of the water pressure must be assumed to be at the same level as the forcing pumps, or more correctly, the water discharged from the receivers to be at the same level as the surface of the water from which the pumps draw their supply. In this case the general efficiency of transmission is the product of three partial efficiencies, which correspond exactly to those mentioned with regard to compressed air. The height of lift, contained in the numerator of the fraction which expresses the efficiency of the pumps, is not to be taken as the difference in level between the surface of the water in the reservoir and the surface of the water whence the pumps draw their supply; but as this difference in level, plus the loss of pressure in the suction pipe, which is usually very short, and plus the loss in the channel to the reservoir, which may be very long. A similar loss of initial pressure affects the efficiency of the discharge channel. The reservoir, if of sufficient capacity, may become an important store of power, while the compressed air reservoir can only do so to a very limited extent.

Omitting the subject of the pumps, and passing on at once to the discharge main, the author may first point out that the distinction between the ascending and descending mains of the system is of no importance, for two reasons: first, that nothing prevents the motors being supplied direct from the first alone; and second, that the one is not always distinct from the other. In fact, the reservoir may be connected by a single branch pipe with the system which goes from the pumps to the motors; it may even be placed at the extreme end of this system beyond the motors, provided always that the supply pipe is taken into it at the bottom. The same formula may be adopted for the loss of initial pressure in water pipes as for compressed air pipes, viz.,

p1 - p 64 b1
------- = --------- L Q² ± h;
[Delta] [pi]² D^5

[TEX: \frac{p_1 - p}{\Delta} = \frac{64 b_1}{\pi^2 D^5} L Q^2 \pm h]

h being the difference of level between the two ends of the portion of conduit of length, L, and the sign + or - being used according as the conduit rises or falls. The specific weight, [delta], is constant, and the quotients, p1/[delta] and p/[delta], represent the heights, z and z1, to which the water could rise above the pipes, in vertical tubes branching from it, at the beginning and end of the transit. The values assigned to the coefficient b1 in France, are those determined by D'Arcy. For new cast-iron pipes he gives b1 - 0.0002535 + 1/D 0.000000647; and recommends that this value should be doubled, to allow for the rust and incrustation which more or less form inside the pipes during use. The determination of this coefficient has been made from experiments where the pressure has not exceeded four atmospheres; within these limits the value of the coefficient, as is generally admitted, is independent of the pressure. The experiments made by M. Barret, on the pressure pipes of the accumulator at the Marseilles docks, seem to indicate that the loss of pressure would be greater for high pressures, everything else being equal. This pipe, having a diameter of 0.127 m. (5 in.), was subjected to an initial pressure of 52 atmospheres. The author gives below the results obtained for a straight length 320 m. (1050 ft) long; and has placed beside them the results which D'Arcy's formula would give.

Loss of head, in meters or ft. respectively per 100 meters or ft. run of pipes. +-----------------^-------------------+ | | Calculated loss. +-----------^-----------+ | | Velocity of flow Actual loss per second. observed. Old pipes. New pipes. Meters. Feet. Met. or Ft. Met. or Ft. Met. or Ft. 0.25 0.82 1.5 0.12 0.06 0.50 1.64 2.5 0.48 0.24 0.75 2.46 3.7 1.08 0.54 1.00 3.28 5.5 1.92 0.96 1.25 4.10 6.1 3.00 1.50 1.50 4.92 7.3 4.32 2.16 1.75 5.74 8.0 5.88 2.94 2.00 6.56 10.2 7.68 3.84 2.25 7.38 11.7 9.72 4.86 2.50 8.20 14.0 12.00 6.00

Moreover, these results would appear to indicate a different law from that which is expressed by the formula b1 u², as is easy to see by representing them graphically. It would be very desirable that fresh experiments should be made on water pipes at high pressure, and of various diameters. Of machines worked by water pressure the author proposes to refer only to two which appear to him in every respect the most practical and advantageous. One is the piston machine of M. Albert Schmid, engineer at Zurich. The cylinder is oscillating, and the distribution is effected, without an eccentric, by the relative motion of two spherical surfaces fitted one against the other, and having the axis of oscillation for a common axis. The convex surface, which is movable and forms part of the cylinder, serves as a port face, and has two ports in it communicating with the two ends of the cylinder. The concave surface, which is fixed and plays the part of a slide valve, contains three openings, the two outer ones serving to admit the pressure water, and the middle one to discharge the water after it has exerted its pressure. The piston has no packing. Its surface of contact has two circumferential grooves, which produce a sort of water packing acting by adhesion. A small air chamber is connected with the inlet pipe, and serves to deaden the shocks. This engine is often made with two cylinders, having their cranks at right angles.

The other engine, which is much less used, is a turbine on Girard's system, with a horizontal axis and partial admission, exactly resembling in miniature those which work in the hydraulic factory of St. Maur, near Paris. The water is introduced by means of a distributer, which is fitted in the interior of the turbine chamber, and occupies a certain portion of its circumference. This turbine has a lower efficiency than Schmid's machine, and is less suitable for high pressures; but it possesses this advantage over it, that by regulating the amount of opening of the distributer, and consequently the quantity of water admitted, the force can be altered without altering the velocity of rotation. As it admits of great speeds, it could be usefully employed direct, without the interposition of spur wheels or belts for driving magneto-electric machines employed for the production of light, for electrotyping, etc.

In compressed air machines the losses of pressure due to incomplete expansion, cooling, and waste spaces, play an important part. In water pressure machines loss does not occur from these causes, on account of the incompressibility of the liquid, but the frictions of the parts are the principal causes of loss of power. It would be advisable to ascertain whether, as regards this point, high or low pressures are the most advantageous. Theoretical considerations would lead the author to imagine that for a piston machine low pressures are preferable. In conclusion, the following table gives the efficiencies of a Girard turbine, constructed by Messrs. Escher Wyss & Co., of Zurich, and of a Schmid machine, as measured by Professor Fliegnor, in 1871:

ESCHER WYSS & CO'S TURBINE.

Effective Head of Water. Revolutions Efficiency. per minute. Meters. Feet. Revs. Per cent. 20.7 67.9 628 68.5 20.7 67.9 847 47.4 24.1 79.0 645 68.5 27.6 90.5 612 65.7 27.6 90.5 756 68.0 31.0 101.7 935 56.9 31.0 101.7 1,130 35.1

SCHMID MOTOR.

8.3 27.2 226 37.4 11.4 37.4 182 67.4 14.5 47.6 254 53.4 17.9 58.7 157 86.2 20.7 67.9 166 89.6 20.7 67.9 225 74.6 24.1 79.0 238 76.7 24.1 79.0 389 64.0 27.6 90.5 207 83.9

It will be observed that these experiments relate to low pressures; it would be desirable to extend them to higher pressures.

IV. _Transmission by Electricity._--However high the efficiency of an electric motor may be, in relation to the chemical work of the electric battery which feeds it, force generated by an electric battery is too expensive, on account of the nature of the materials consumed, for a machine of this kind ever to be employed for industrial purposes. If, however, the electric current, instead of being developed by chemical work in a battery, is produced by ordinary mechanical power in a magneto-electric or dynamo-electric machine, the case is different; and the double transformation, first of the mechanical force into an electric current, and then of that current into mechanical force, furnishes a means for effecting the conveyance of the power to a distance.

It is this last method of transmission which remains to be discussed. The author, however, feels himself obliged to restrict himself in this matter to a mere summary; and, indeed, it is English physicists and engineers who have taken the technology of electricity out of the region of empiricism and have placed it on a scientific and rational basis. Moreover, they are also taking the lead in the progress which is being accomplished in this branch of knowledge, and are best qualified to determine its true bearings. When an electric current, with an intensity, i, is produced, either by chemical or mechanical work, in a circuit having a total resistance, R, a quantity of heat is developed in the circuit, and this heat is the exact equivalent of the force expended, so long as the current is not made use of for doing any external work. The expression for this quantity of heat, per unit of time, is Ai²R; A being the thermal equivalent of the unit of power corresponding to the units of current and resistance, in which i and R are respectively expressed. The product, i²R, is a certain quantity of power, which the author proposes to call _power transformed into electricity_. When mechanical power is employed for producing a current by means of a magneto-electric or dynamo-electric machine--or, to use a better expression, by means of a _mechanical generator of electricity_--it is necessary in reality to expend a greater quantity of power than i²R in order to make up for losses which result either from ordinary friction or from certain electro magnetic reactions which occur. The ratio of the quantity, i²R, to the power, W, actually expended per unit of time is called the efficiency of the generator. Designating it by K, we obtain, W = i²R/K. It is very important to ascertain the value of this efficiency, considering that it necessarily enters as a factor into the evaluation of all the effects to be produced by help of the generator in question. The following table gives the results of certain experiments made early in 1879, with a Gramme machine, by an able physicist, M Hagenbach, Professor at the University at Basle, and kindly furnished by him to the author:

Revolutions per minute 935 919.5 900.5 893

Total resistance in Siemens' units 2.55 3.82 4.94 6.06

Total resistance in absolute units 2.435 3.648 4.718 5.787
x10^9 x10^9 x10^9 x10^9

Intensity in chemical units 17.67 10.99 8.09 6.28

Intensity in absolute units 2.828 1.759 1.295 1.005

Work done i²R in absolute units 1948.6 1129.2 791.3 584.9
x10^7 x10^7 x10^7 x10^7

Work done i²R in kilogrammes 198.6 115.1 80.66 59.62

Power expended in kilogrammes 301.5 141.0 86.25 83.25

Efficiency, per cent. 65.9 81.6 93.5 71.6

M. Hagenbach's dynamometric measurements were made by the aid of a brake. After each experiment on the electric machine, he applied the brake to the engine which he employed, taking care to make it run at precisely the same speed, with the same pressure of steam, and with the same expansion as during experiment. It would certainly be better to measure the force expended during and not after the experiment, by means of a registering dynamometer. Moreover, M. Hagenbach writes that his measurements by means of the brake were very much prejudiced by external circumstances; doubtless this is the reason of the divergences between the results obtained.

About the same time Dr. Hopkinson communicated to this institution the results of some very careful experiments made on a Siemens machine. He measured the force expended by means of a registering dynamometer, and obtained very high coefficients of efficiency, amounting to nearly 90 per cent. M. Hagenbach also obtained from one machine a result only a little less than unity. Mechanical generators of electricity are certainly capable of being improved in several respects, especially as regards their adaptation to certain definite classes of work. But there appears to remain hardly any margin for further progress as regards efficiency. Force transformed into electricity in a generator may be expressed by i [omega] M C; [omega] being the angular velocity of rotation; M the magnetism of one of the poles, inducing or induced, which intervenes; and C a constant specially belonging to each apparatus, and which is independent of the units adopted. This constant could not be determined except by an integration practically impossible; and the product, M C, must be considered indivisible. Even in a magneto-electric machine (with permanent inducing magnets), and much more in a dynamo-electric machine (inducing by means of electro-magnets excited by the very current produced) the product, M C, is a function of the intensity. From the identity of the expressions, i²R and i [omega] M C we obtain the relation M C = IR/[omega] which indicates the course to be pursued to determine experimentally the law which connects the variations of M C with those of i. Some experiments made in 1876, by M. Hagenbach, on a Gramme dynamo-electric machine, appear to indicate that the magnetism, M C, does not increase indefinitely with the intensity, but that there is some maximum value for this quantity. If, instead of working a generator by an external motive force, a current is passed through its circuit in a certain given direction, the movable part of the machine will begin to turn in an opposite direction to that in which it would have been necessary to turn it in order to obtain a current in the aforesaid direction. In virtue of this motion the electro-magnetic forces which are generated may be used to overcome a resisting force. The machine will then work as a motor or receiver. Let i be the intensity of the external current which works the motor, when the motor is kept at rest. If it is now allowed to move, its motion produces, in virtue of the laws of induction, a current in the circuit of intensity, i1, in the opposite direction to the external current; the effective intensity of the current traversing the circuit is thus reduced to i - i1. The intensity of the counter current is given, like that of the generating current, by the equation, i1²R = i1 [omega]1 M1 C1, or i1R = [omega]1 M1 C1, the index, 1, denoting the quantities relating to the motor. Here M1 C1 is a function of i - i1, not of i. As in a generator the force transformed into electricity has a value, i [omega] M C, so in a motor the force developed by electricity is (i - i1) [omega]1 M1 C1. On account, however, of the losses which occur, the effective power, that is the disposable power on the shaft of the motor, will have a smaller value, and in order to arrive at it a coefficient of efficiency, K1, must be added. We shall then have W1 = K1 (i-i1) [omega]1 M1 C1. The author has no knowledge of any experiments having been made for obtaining this efficiency, K1. Next let us suppose that the current feeding the motor is furnished by a generator, so that actual transmission by electricity is taking place. The circuit, whose resistance is R, comprises the coils, both fixed and movable, of the generator and motor, and of the conductors which connect them. The intensity of the current which traverses the circuit had the value, i, when the motor was at rest; by the working of the motor it is reduced to i - i1. The power applied to the generator is itself reduced to W-[(i-i1)[omega] M C]/K. The prime mover is relieved by the action of the counter current, precisely as the consumption of zinc in the battery would be reduced by the same cause, if the battery was the source of the current. The efficiency of the transmission is W1/W. Calculation shows that it is expressed by the following equations:W1/W = K K1 [([omega]11 M1 C1)/([omega]1 M C)], or = K K1 [([omega]11 M1 C)/([omega]11 M1 C1 + (i-i1) R)]; expressions in which it must be remembered M C and M1 C1 are really functions of (i-i1). This efficiency is, then, the product of three distinct factors, each evidently less than unity, namely, the efficiency belonging to the generator, the efficiency belonging to the motor, and a third factor depending on the rate of rotation of the motor and the resistance of the circuit. The influence which these elements exert on the value of the third factor cannot be estimated, unless the law is first known according to which the magnetisms, M C, M1 C C1, vary with the intensity of the current.

GENERAL RESULTS.

Casting a retrospective glance at the four methods of transmission of power which have been examined, it would appear that transmission by ropes forms a class by itself, while the three other methods combine into a natural group, because they possess a character in common of the greatest importance. It may be said that all three involve a temporary transformation of the mechanical power to be utilized into potential energy. Also in each of these methods the efficiency of transmission is the product of three factors or partial efficiencies, which correspond exactly--namely, first, the efficiency of the instrument which converts the actual energy of the prime mover into potential energy; second, the efficiency of the instrument which reconverts this potential energy into actual energy, that is, into motion, and delivers it up in this shape for the actual operations which accomplish industrial work; third, the efficiency of the intermediate agency which serves for the conveyance of potential energy from the first instrument to the second.

This last factor has just been given for transmission by electricity. It is the exact correlative of the efficiency of the pipe in the case of compressed air or of pressure water. It is as useful in the case of electric transmission, as of any other method, to be able, in studying the system, to estimate beforehand what results it is able to furnish, and for this purpose it is necessary to calculate exactly the factors which compose the efficiency.

In order to obtain this desirable knowledge, the author considers that the three following points should form the aim of experimentalists: First, the determination of the efficiency, K, of the principal kinds of magneto-electric, or dynamo-electric machines working as generators; second, the determination of the efficiency, K1, of the same machines working as motors; third, the determination of the law according to which the magnetism of the cores of these machines varies with the intensity of the current. The author is of opinion that experiments made with these objects in view would be more useful than those conducted for determining the general efficiency of transmission, for the latter give results only available under precisely similar conditions. However, it is clear that they have their value and must not be neglected.

There are, moreover, many other questions requiring to be elucidated by experiment, especially as regards the arrangement of the conducting wires: but it is needless to dwell further upon this subject, which has been ably treated by many English men of science--for instance, Dr. Siemens and Professor Ayrton. Nevertheless, for further information the author would refer to the able articles published at Paris, by M. Mascart, in the _Journal de Physique_, in 1877 and 1878. The author would gladly have concluded this paper with a comparison of the efficiencies of the four systems which have been examined, or what amounts to the same thing--with a comparison of the losses of power which they occasion. Unfortunately, such a comparison has never been made experimentally, because hitherto the opportunity of doing it in a demonstrative manner has been wanting, for the transmission of power to a distance belongs rather to the future than to the present time. Transmission by electricity is still in its infancy; it has only been applied on a small scale and experimentally.

Of the three other systems, transmission by means of ropes is the only one that has been employed for general industrial purposes, while compressed air and water under pressure have been applied only to special purposes, and their use has been due much more to their special suitableness for these purposes than from any considerations relative to loss of power. Thus the effective work of the compressed air used in driving the tunnels through the Alps, assuming its determination to be possible, was undoubtedly very low; nevertheless, in the present state of our appliances it is the only process by which such operations can be accomplished. The author believes that transmission by ropes furnishes the highest proportion of useful work, but that as regards a wide distribution of the transmitted power the other two methods, by air and water, might merit a preference.

* * * * *

THE HOTCHKISS REVOLVING GUN.

The Hotchkiss revolving gun, already adopted in the French navy and by other leading European nations, has been ordered for use in the German navy by the following decree of the German Emperor, dated January 11 last: "On the report made to me, I approve the adoption of the Hotchkiss revolving cannon as a part of the artillery of my navy; and each of my ships, according to their classification, shall in general be armed with this weapon in such a manner that every point surrounding the vessel may be protected by the fire of at least two guns at a minimum range of 200 meters."

* * * * *

THALLIUM PAPERS AS OZONOMETERS.

Schoene has given the results of an extended series of experiments on the use of thallium paper for estimating approximately the oxidizing material in the atmosphere, whether it be hydrogen peroxide alone, or mixed with ozone, or perhaps also with other constituents hitherto unknown. The objection to Schönbein's ozonometer (potassium iodide on starch paper) and to Houzeau's ozonometer (potassium iodide on red litmus paper) lies in the fact that their materials are hygroscopic, and their indications vary widely with the moisture of the air. Since dry ozone does not act on these papers, they must be moistened; and then the amount of moisture varies the result quite as much as the amount of ozone. Indeed, attention has been called to the larger amount of ozone near salt works and waterfalls, and the erroneous opinion advanced that ozone is formed when water is finely divided. And Böttger has stated that ozone is formed when ether is atomized; the fact being that the reaction he observed was due to the H_2O_2 always present in ether. Direct experiments with the Schönbein ozonometer and the psychrometer gave parallel curves; whence the author regards the former as only a crude hygrometer. These objections do not lie against the thallium paper, the oxidation to brown oxide by either ozone or hydrogen peroxide not requiring the presence of moisture, and the color, therefore, being independent of the hygrometric state of the air. Moreover, when well cared for, the papers undergo no farther change of color and may be preserved indefinitely. The author prepares the thallium paper a few days before use, by dipping strips of Swedish filtering paper in a solution of thallous hydrate, and drying. The solution is prepared by pouring a solution of thallous sulphate into a boiling solution of barium hydrate, equivalent quantities being taken, the resulting solution of thallous hydrate being concentrated in vacuo until 100 c.c. contains 10 grammes Tl(OH). For use the strips are hung in the free air in a close vessel, preferably over caustic lime, for twelve hours. Other papers are used, made with a two per cent. solution. These are exposed for thirty-six hours. The coloration is determined by comparison with a scale having eleven degrees of intensity upon it. Compared with Schönbein's ozonometer, the results are in general directly opposite. The thallium papers show that the greatest effect is in the daytime, the iodide papers that it is at night. Yearly curves show that the former generally indicate a rise when the latter give a fall. The iodide curve follows closely that of relative humidity, clouds, and rain; the thallium curve stands in no relation to it. A table of results for the year 1879 is given in monthly means, of the two thallium papers, the ozonometer, the relative humidity, cloudiness, rain, and velocity of wind.--_G. F. B., in Ber. Berl. Chem. Ces._

* * * * *

THE AUDIPHONE IN ENGLAND.

The audiphone has been recently tried in the Board School for Deaf and Dumb at Turin street, Bethnal Green, with very satisfactory results--so satisfactory that the report will recommend its adoption in the four schools which the London Board have erected for the education of the deaf and dumb. Some 20 per cent. of the pupils in deaf and dumb schools have sufficient power of hearing when assisted by the audiphone to enable them to take their places in the classes of the ordinary schools.

* * * * *

CONDUCTIVITY OF MOIST AIR.

Many physical treatises still assert that moist air conducts electricity, though Silberman and others have proved the contrary. An interesting experiment bearing on this has been described lately by Prof. Marangoni. Over a flame is heated some water in a glass jar, through the stopper of which passes a bent tube to bell-jar (held obliquely), which thus gets filled with aqueous vapor. The upper half of a thin Leyden jar charged is brought into the bell-jar, and held there four or five seconds; it is then found entirely discharged. That the real cause of this, however, is condensation of the vapor on the part of the glass that is not coated with tin foil (the liquid layer acting by conduction) can be proved; for if that part of the jar be passed several times rapidly through the flame, so as to heat it to near 100° C., before inserting in the bell-jar, a different effect will be had; the Leyden jar will give out long sparks after withdrawal. This is because the glass being heated no longer condenses the vapor on its surface, and there is no superficial conduction, as in the previous case.

* * * * *

FLOATING PONTOON DOCK.

Considerable attention has been given for some years past to the subject of floating pontoon docks by Mr. Robert Turnbull, naval architect, of South Shields, Eng., who has devised the ingenious arrangement which forms the subject of the annexed illustration. The end aimed at and now achieved by Mr. Turnbull was so to construct floating docks or pontoons that they may rise and fall in a berth, and be swung round at one end upon a center post or cylinder--nautically known as a dolphin--projecting from the ground at a slight distance from the berth. The cylinder is in deep water, and, when the pontoon is swung and sunk to the desired depth by letting in the necessary amount of water, a vessel can be floated in and then secured. The pontoon, with the vessel on it, is then raised by pumping out the contained water until she is a little above the level of the berth. The whole is then swung round over the berth, the vessel then being high and dry to enable repairs or other operations to be conducted. For this purpose, one end of the pontoon is so formed as to enable it to fit around the cylinder, and to be held to it as to a center or fulcrum, about which the pontoon can be swung. The pontoon is of special construction, and has air-chambers at the sides placed near the center, so as to balance it. It also has chambers at the ends, which are divided horizontally in order that the operation of submerging within a berth or in shallow water may be conducted without risk, the upper chambers being afterwards supplied with water to sink the pontoon to the full depth before a vessel is hauled in. When the ship is in place, the pontoon with her is then lifted above the level of the berth in which it has to be placed, and then swung round into the berth. In some cases, the pontoon is provided with a cradle, so that, when in berth, the vessel on the cradle can be hauled up a slip with rails arranged as a continuation of the cradle-rails of the pontoon, which can be then furnished with another cradle, and another vessel lifted.

It is this latter arrangement which forms the subject of our illustration, the vessel represented being of the following dimensions: Length between perpendiculars, 350 feet; breadth, moulded, 40 feet; depth, moulded, 32 feet; tons, B. M., 2,600; tons net, 2,000. At A, in fig. 1, is shown in dotted lines a portion of the vessel and pontoon, the ship having just been hauled in and centered over the keel blocks. At B, is shown the pontoon with the ship raised and swung round on to a low level quay. Going a step further in the operation, we see at C, the vessel hauled on to the slipways on the high-level quay. In this case the cylinder is arranged so that the vessel may be delivered on to the rails or slips, which are arranged radially, taking the cylinder as the center. There may be any number of slips so arranged, and one pontoon may be made available for several cylinders at the deep water parts of neighboring repairing or building yards, in which case the recessed portion of the pontoon, when arranged around the cylinder, has stays or retaining bars fitted to prevent it leaving the cylinder when the swinging is taking place, such as might happen in a tideway.

The arrangements for delivering vessels on radial slips is seen in plan at fig. 2, where A represents the river or deep water; B is the pontoon with the vessel; C being the cylinder or turning center; D is the low-level quay on to which the pontoon carrying the ship is first swung; E is the high-level quay with the slip-ways; F is an engine running on rails around the radial slips for drawing the vessels with the cradle off the pontoon, and hauling them up on to the high-level quay; and G shows the repairing shops, stores, and sheds. A pontoon attached to a cylinder may be fitted with an ordinary wet dock; and then the pontoon, before or after the vessel is upon it, can be slewed round to suit the slips up which the vessel has to be moved, supposing the slips are arranged radially. In this case, the pivot end of the pontoon would be a fixture, so to speak, to the cylinder.

The pontoon may also be made available for lifting heavy weights, by fitting a pair of compound levers or other apparatus at one end, the lifting power being in the pontoon itself. In some cases, in order to lengthen the pontoon, twenty-five or fifty foot lengths are added at the after end. When not thus engaged, those lengths form short pontoons suitable for small vessels.--_Iron_.

* * * * *

WEIRLEIGH, BRENCHLEY, KENT.

Some few years since, Mr. Harrison Weir (whose drawings of natural history are known probably to a wider circle of the general public than the works of most artists), wishing to pursue his favorite study of animals and horticulture, erected on the steep hillside of the road leading from Paddock Wood to Brenchley, a small "cottage ornée" with detached studio. Afterward desiring more accommodation, he carried out the buildings shown in our illustrations. Advantage has been taken of the slope of the hill on one side, and the rising ground in the rear on the other, to increase the effect of the buildings and meet the difficulty of the levels. The two portions--old, etched, and new, shown as black--are connected together by a handsome staircase, which is carried up in the tower, and affords access to the various levels. The materials are red brick, with Bathstone dressings, and weather-tiling on the upper floors. Black walnut, pitch pine, and sequoias have been used in the staircase, and joiner's work to the principal rooms. The principal stoves are of Godstone stone only, no iron or metal work being used. The architects are Messrs. Wadmore & Baker, of 35 Great St. Helens, E.C.; the builders, Messrs. Penn Brothers, of Pembury, Kent.--_Building News_.

* * * * *

RAPID BREATHING AS A PAIN OBTUNDER IN MINOR SURGERY, OBSTETRICS, THE GENERAL PRACTICE OF MEDICINE AND OF DENTISTRY.

[Footnote: Read before the Philadelphia County Medical Society, May 12, 1880, by W. G. A. Bonwill, M.D., D.D.S., Philadelphia.]

Through the kind invitation of your directors, I am present to give you the history of "rapid breathing" as an analgesic agent, as well as my experience therein since I first discovered it. It is with no little feeling of modesty that I appear before such a learned and honorable body of physicians and surgeons, and I accept the privilege as a high compliment. I trust the same liberal spirit which prompted you to call this subject to the light of investigation will not forsake you when you have heard all I have to say and you sit in judgment thereon. Sufficient time has now elapsed since the first promulgation of the subject for the shafts of ridicule to be well nigh spent (which is the common logic used to crush out all new ideas), and it is to be expected that gentlemen will look upon it with all the charity of a learned body, and not be too hasty to condemn what they have had but little chance to investigate; and, of course, have not practiced with that success which can only come from an intelligent understanding of its application and _modus operandi_.

Knowing the history of past discoveries, I was well prepared for the crucible. I could not hope to be an exception. But, so far, the medical profession have extended me more favor than I have received at the hands of the dental profession.

My first conception of the analgesic property of a pain obtunder in contradistinction to its anaesthetic effect, which finally led to the discovery of the inhalation of common air by "rapid breathing," was in 1855 or 1856, while performing upon my own teeth certain operations which gave me intense pain (and I could not afford to hurt myself) without a resort to ether and chloroform. These agents had been known so short a time that no one was specially familiar with their action. Without knowing whether I could take chloroform administered by myself, and at the same time perform with skill the excavation of extremely sensitive dentine or tooth-bone, as if no anaesthetic had been taken, and not be conscious of pain, was more than the experience of medical men at that time could assure me. But, having a love for investigation of the unknown, I prepared myself for the ordeal. By degrees I took the chloroform until I began to feel very plainly its primary effects, and knowing that I must soon be unconscious, I applied the excavator to the carious tooth, and, to my surprise, found no pain whatever, but the sense of touch and hearing were marvelously intensified. The small cavity seemed as large as a half bushel; the excavator more the size of an ax; and the sound was equally magnified. That I might not be mistaken, I repeated the operation until I was confident that anaesthetics possessed a power not hitherto known--that of analgesia. To be doubly certain, I gave it in my practice, in many cases with the same happy results, which saved me from the risks incident to the secondary effects of anaesthetics, and which answered for all the purposes of extracting from one to four teeth. Not satisfied with any advance longer than I could find a better plan, I experimented with the galvanic current (to and fro) by so applying the poles that I substituted a stronger impression by electricity from the nerve centers or ganglia to the peripheries than was made from the periphery to the brain. This was so much of a success that I threw aside chloroform and ether in removing the living nerve of a tooth with instruments instead of using arsenic; and for excavating sensitive caries in teeth, preparatory to filling, as well as many teeth extracted by it. But this was short-lived, for it led to another step. Sometimes I would inflict severe pain in cases of congested pulps or from its hasty application, or pushing it to do too much, when my patient invariably would draw or inhale the breath _very forcibly and rapidly_. I was struck with the repeated coincidence, and was led to exclaim: "Nature's anaesthetic." This then reminded me of boyhood's bruises. The involuntary action of every one who has a finger hurt is to place it to the mouth and draw violently in the air and hold it for an instant, and again repeat it until the pain is subdued. The same action of the lungs occurs, except more powerfully, in young children who take to crying when hurt. It will be noticed they breathe very rapidly while furiously crying, which soon allays the irritation, and sleep comes as the sequel. Witness also when one is suddenly startled, how violently the breath is taken, which gives relief. The same thing occurs in the lower animals when pain is being inflicted at the hand of man.

This was advance No. 3, and so sure was I of this new discovery, that I at once made an application while removing decay from an extremely sensitive tooth. To be successful, I found I must make the patient take the start, and I would follow with a thrust from the excavator, which move would be accomplished before the lungs could be inflated. This was repeated for at least a minute, until the operation was completed, I always following immediately or synchronously with the inhalation.

This led to step No. 4, which resulted in its application to the extracting of teeth and other operations in minor surgery.

Up to this time I had believed the sole effect of the rapid inhalation was due to mere diversion of the will, and this was the only way nature could so violently exert herself--that of controlling the involuntary action of the lungs to her uses by the _safety valve_, or the voluntary movement.

The constant breathing of the patient for thirty seconds to a minute left him in a condition of body and mind resembling the effects of ether and chloroform in their primary stages. I could but argue that the prolonged breathing each time had done it; and, if so, then there must be some specific effect over and above the mere diversion by the will. To what could it be due? To the air alone, which went in excess into the lungs in the course of a minute! Why did I not then immediately grasp the idea of its broader application as now claimed for it? It was too much, gentlemen, for that hour. Enough had been done in this fourth step of conception to rest in the womb of time, until by evolution a higher step could be made at the maturity of the child. Being self-satisfied with my own baby, I watched and caressed it until it could take care of itself, and my mind was again free for another conception.

The births at first seemed to come at very short intervals; but see how long it was between the fourth and the fifth birth. It was soon after that my mind became involved in inventions--a hereditary outgrowth--and the electric mallet and then the dental engine, the parent of your surgical engine, to be found in the principal hospitals of this city, took such possession of my whole soul, that my air analgesic was left slumbering. It was not until August, 1875--nineteen years after--that it again came up in full force, without any previous warning.

This time it was no law of association that revived it; but it seemed the whispering of some one in the air--some ethereal spirit, if you please--which instituted it, and advanced the following problem: "Nitrous oxide gas is composed of the same elements as ordinary air, with a larger equivalent of oxygen, except it is a chemical compound, not a mechanical mixture, and its anaesthetic effects are said to be due to the excess of oxygen. If this be a fact, then why can you not produce a similar effect by rapid breathing for a minute, more or less, by which a larger quantity of oxygen is presented in the lungs for absorption by the blood?"

This query was soon answered by asking myself another: "If the rapid inhalation of air into the lungs does not increase the heart's action and cause it to drive the blood in exact ratio to the inhalations, then _I can_ produce partial anaesthesia from this excess of oxygen brought about by the voluntary movements over their ordinary involuntary action of the lungs." The next question was: Will my heart be affected by this excess of air in the lungs to such an extent that there will be a full reciprocity between them? Without making any trial of it, I argued that, while there is no other muscular movement than that of the chest as under the control of the will, and as nature has given to the will the perfect control over the lungs to supply more or less air, as is demanded by the pneumogastric nerve for the immediate wants of the economy, when the _involuntary action_ is not sufficient; and the heart not being under the control of the will, and its action never accelerated or diminished except by a specific poison, or from the general activity of the person in violent running or working, the blood is forced into the heart faster and must get rid of it, when a larger supply of oxygen is demanded and rapid breathing must occur, or asphyxia result. I was not long in deciding that the heart _would not be accelerated_ but a trifle--say a tenth--and, under the circumstances, I said: "The air _is_ an anaesthetic."

From this rapid course of argument, I was so profoundly convinced of its truth, that without having first tried it upon my own person, I would have sat where I was, upon the curbstone, and had a tooth removed with the perfect expectation of absence of pain and of still being conscious of touch. While yet walking with my children, I commenced to breathe as rapidly as possible, and, as anticipated, found my steps growing shorter and shorter, until I came to a stand, showing to my mind clearly that my argument in advance was right, so far as locomotion was concerned; and, upon referring to my pulse, I found but little acceleration.

To what other conclusion could I arrive from this argument, with the foundation laid nineteen years before, when I established on my own person by experiment the fact of analgesia as induced from chloroform, with the many experiments in rapid respiration on tooth bone?

From this moment until its first application to the extraction of a tooth you can well imagine my suspense. That I might not fail in the very first attempt, I compelled myself and others in my household to breathe rapidly to investigate the phenomenon. This gave me some idea as to the proper method of proceeding in its administering.

The first case soon appeared, and was a perfect success, going far beyond my anticipations, for the effect was such as to produce a partial paralysis of the hands and arms to the elbow. Again and again I tried it in every case of extraction and many other experiments, doubting my own senses for a long time at a result so anomalous and paradoxical. I was reminded just here of a phenomenon which gave me additional proof--that of blowing a dull fire to revive it. For a minute or so one blows and blows in rapid succession until, rising from the effort, a sense of giddiness for a few moments so overcomes that the upright position is with difficulty maintained. In this condition you are fitted for having a tooth extracted or an abscess lanced.

Believing that I had something new to offer which might be of use to suffering humanity, I read the first article upon it Nov. 17, 1875, before the Franklin Institute. Shortly after I was invited before the Northern Medical Society of this city to address them thereon. A number of medical gentlemen have been using it in their practice, while the bulk of them have spurned it as "negative" and preposterous, without an effort at trying it, which I can _now_ very well understand.

Unless one is aware of the fact that in the use of any agent which has the power to suspend the volition, it can be taken to that point where he is still conscious of _touch and hearing_, and at the same time not cognizant of pain inflicted, the action of rapid breathing could not be understood. And I regret to say that of three-fourths of the medical men I have talked with on the subject they had not been aware of such a possibility from ether and chloroform. Until this analgesic state could be established in their minds it was impossible to convince them that the excess of oxygen, as obtained by rapid breathing, could be made to produce a similar effect. _I_ should have been as reluctant as any one to believe it, had I not personally experienced the effect while performing an operation which would otherwise have been very painful. Such a result could not well be reached by any course of reasoning.

Has it proven in my practice what has been claimed for it--a substitute for the powerful anaesthetics in minor operations in surgery? Most emphatically, yes! So completely has it fulfilled its humble mission in my office, that I can safely assert there has not been more than five per cent. of failures. I have given it under all circumstances of diseased organs, and have seen no other than the happiest results in its after effects. It may well be asked just here: Why has it not been more generally and widely used by the dental profession as well as the medical, if it is really what is claimed for it? The most satisfactory and charitable answer to be given is, the failure upon their part to comprehend the _fact_ as existing in chloroform and ether that there is such a state as analgesia; or, in other words, that the animal economy is so organized, while the sense of touch is not destroyed, but rather increased, the mind of the subject fails to perceive a sense of pain when anaesthetics are given, and the effects are manifested in the primary stage. As I before intimated, such is the knowledge possessed by most of those who administer ether and chloroform. This was enough to cause nearly every one to look upon it as a bubble or air castle. Many gentlemen told me they tried it upon themselves, and, while it affected them very seriously by giddiness, they still _retained consciousness_; and, such being the case, no effect could be produced for obtunding pain. Others told me they were afraid to continue the breathing alarmed at the vertigo induced. And the practitioner who has adopted it more effectively than any other laughed at me when I first told him of the discovery; but his intimate association with me changed his views after much explanation and argument between us.

It was hardly to be expected that without this knowledge of analgesia, and without any explanation from me as to the _modus operandi_ of rapid breathing, other than a few suggestions or directions as to how the effect was induced, even the most liberal of medical men should be able to make it effective, or have the least disposition to give it a preliminary trial upon themselves, and, of course, would not attempt it upon a patient. Notwithstanding, it found a few adherents, but only among my personal _medical_ friends, with whom I had an opportunity to explain what I believed its physiological action, and the cases of success in my own practice. To this I have submitted as among the inevitable in the calendar of discoveries of all grades.

My own profession have attempted to _ridicule_ it out of its birthright and possible existence, which style of argument is not resorted to by true logicians.

To all this I can truly say I have not for one moment faltered. I could afford to wait. The liberality of this society alone fully compensates for the seeming indisposition of the past, believing that it is proper that every advance should be confronted, and, if in time found worthy, give it God speed.

From its first conception I have diligently labored to solve its _modus operandi_, and the doubt in my own mind as to whether I could be mistaken in my observations. I asked the opinion of our best chemical teachers if air could have such effect. One attributed it to oxygen stimulation, and the other to nitrogen. Another gentleman told me the medical profession had come to the conclusion that it was possible for me to thus extract teeth, but it was due solely to my strong _personal magnetism_ (which power I was not before aware I possessed).

Now, from what I have related of the successive and natural steps which finally culminated in this process or plan of analgesia induced by an excess of ordinary air taken forcibly into the lungs above what is necessary for life, and from what I shall state as to the apparently anomalous or paradoxical effects, with its physiological action, and the simple tests made upon each of my patients, I shall trust to so convince you of its plausibility and possibility that it will be made use of in hundreds of minor operations where ether and chloroform are now used.

Aside from my assertion and that of its friends, that the effects can be produced by air alone, you must have some light shed upon the causes of its physiological action, which will appeal to your _medical_ reason.

To assign an action to any drug is difficult, and in the cases of ether and the other anaesthetics a quarter of a century still finds many conflicting opinions. This being true, you will deal leniently with me for the opinion I hold as to their analgesic action. Of course it will be objected to, for the unseen is, to a great extent, unknowable. Enough for my argument, however; it seems to suit the case very well without looking for another; and while it was based on the phenomenon resulting from many trials, and not the trials upon it as a previous theory, I shall be content with it until a better one can be found.

What is it I claim as a new discovery, and the facts and its philosophy?