NATURE 



41 



THURSDAY, JANUARY 12, 1893. 



AMERICAN MECHANISM. 

 Modern Mechanism. Edited by Park Benjamin, LL.B., 

 Ph.D. (London and New York : Macmillan and Co., 

 1892.) 



IN order to appreciate this volume thoroughly, it is 

 necessary in the first instance to consider the reason 

 for its existence. Appleton's " Dictionary of Engineering," 

 an American book, was published in the year 185 1, 

 and was the first to gather in cyclopedic form descriptions 

 of products of American mechanical industry. Some 

 thirty years afterwards it became neces-ary to bring the 

 work up to date, and its complete reconstruction was de- 

 cided upon. The editor observes that no previous work 

 of a technical character had so signally, and so quickly, 

 demonstrated its own usefulness; it rapidly became a 

 recognized standard of American mechanical practice. 

 Owing, however, to the great progress made in mechanical 

 invention, and the marvellous rapidity with which electrical 

 science has advanced, a new record of the results has 

 become necessary, and hence the present volume. 



The list of contributors includes the names of eminent 

 men, well known in this country for their high attain- 

 ments in the different branches of mechanical and 

 electrical engineering, forming a sure guarantee that 

 the information to be gleaned from the pages is valuable 

 and accurate. It would be impossible in the space at 

 our disposal to notice more than a small part of 

 the contents. Some interesting information is to be 

 found on the subject of aerial navigation, more particu- 

 larly the interesting experiments being carried out by Mr. 

 Hiram S. Maxim. Commenting on Prof. Langley's state- 

 ment, that with a flying machine the greater the speed 

 the less would be the power required, Mr. Maxim says : 

 "In navigating the air we may reason as follows : if 

 we make no allowance for skin friction and the resistance 

 of the wires and framework passing through the air — 

 these factors being very small indeed at moderate speeds 

 as vjompared to the resistance offered by the aeroplane— 

 we may assume that with a plane set at an angle of i in 

 I o, and with the whole apparatus weighing 4000 pounds, 

 the push of the screw would have to be 400 pounds. 

 Suppose, now, that the speed should be 30 miles an 

 hour ; the energy required from the engine in useful 

 effect on the machine would be 32 horse-power (30 



<miles = 264o feet per minute, 2640X400^ , Adding 20 



33,000 ^ 



per cent, for slip of screw, it would be 384 horse-power. 

 Suppose, now, that we should increase the speed of the 

 machine to 60 miles an hour, we could reduce the angle 

 of the plane to i in 40, instead of i in 10, because the 

 lifting power of a plane has been found to increase in 

 proportion to the square of its velocity. A plane travelling 

 through the air at the rate of 60 miles an hour, placed at 

 an angle of i in 40, will lift the same as when placed at 

 I in 10, and travelling at half this speed. The push of 

 the screw would therefore have to be only 100 pounds, 

 and it would require 16 horse-power in useful effect to 

 drive the plane. Adding 10 per cent, for the slip of the 

 screw, instead of 20, as for the lower speed, would 

 NO. 12 1 I, VOL. 47] 



increase the engine power required to 17 "6 horse-power. 

 These figures, of course, make no allowance for any loss 

 by atmospheric friction. Suppose 10 per cent, to be 

 consumed in atmospheric resistance when the complete 

 machine was moving 30 miles an hour, it would then 

 require 42"2 horse-power to drive it. Therefore at 30 

 miles an hour only 3"84 horse-power would be consumed 

 by atmospheric friction, while with a speed of 60 miles 

 an hour the engine power required to overcome this 

 resistance would increase eightfold, or 307 horse-power, 

 which, added to 17 6, would make 48' i horse- power for 

 60 miles an hour." 



Mr. Maxim goes on to observe that his experiments 

 show that as much as 133 pounds can be carried with 

 the expenditure of i horse-power, and under certain con- 

 ditions as much as 250 pounds. It will be evident, there- 

 fore, that the question of motors is all important, and 

 that the total weight per horse-power developed must b^ 

 as low as possible. It is stated that the greatest force can 

 be obtained from a compound high-pressure steam 

 engine using steam at 200 to 350 pounds pressure, and 

 such engines have been constructed weighing 300 

 pounds ; the horse-power of these engines is not stated. 



It will be interesting to watch the outcome of these 

 investigations. They indicate that much information is 

 being accumulated, and that sooner or later a successful 

 aerial machine will be forthcoming. 



The question of armour plates has long vexed the soul 

 of the British Admiralty ; many very costly trials have 

 been carried out in order to find the most suitable plate 

 for the service. All these data have probably been 

 known in the States, and that country must have benefited 

 by them. Under this heading we find much information 

 in the book, American experiments being quoted and illus- 

 trated. Naturally, the Americans wish to make their own 

 plates, and wisely endeavour to do so by rolling unly, to 

 do without the heavy expense of forging. These experi- 

 ments show that the high-carbon nickel Harveyed plate 

 is undoubtedly the best plate ever tested. As a result of 

 these trials, orders have been placed for plates for the 

 cruisers under construction. An excellent full-page 

 engraving is given of the U.S. armoured battle ship 

 Indiana, and to judge by the blackness of the smoke she 

 is not using Welsh coal ! The article on steam boilers 

 is well written, and very complete, containing much 

 useful information. Among the many types of boilers 

 illustrated there is a good print of the Yarrow torpedo 

 boat boiler. We miss, however, the familiar Thornycroft 

 boiler, and note an American water tube-boiler for fast 

 launches very like the Thornycroft in the arrangement 

 of the tubes. 



The boilers for marine purposes are purely of the 

 British type, and there is nothing of importance to note 

 on this subject beyond the many experimental results 

 recorded. 



Further on in the book there is an interesting descrip- 

 tion of railway-car heating. We are told that car-heating, 

 in the usual acceptance of the term, has come to mean 

 the heating of railway cars by the use of steam from the 

 locomotive. This is important, showing as it does the 

 direction in which American railway companies are 

 moving in the solution of a problem at present occupying 

 the best attention of engineers in this country. Gener- 



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