164' Prof. Page on Electro-Magnetism as a Moviruj Power. 



led me beyond my strength ; but I have been richly rewarded by the 

 most flattering results. 



The experiments here were not such as could be performed upon 

 the laboratory table ; but were with large masses of iron, weigh- 

 ing in some cases 300 pounds, and helices sometimes twice that 

 weight. 



Adhering to the same size of battery through a long series of ex- 

 periments, and varying the coils and bars, I found, to my great gra- 

 tification, that as I increased the dimensions of each, a corresponding 

 increase of power was exhibited, and the consumption of material, 

 or cost of the power, in some proportion diminished. These results 

 were encouraging and stimulating in the highest degree, and fully 

 justified the undertaking at once of an engine upon a much larger 

 scale than anj- hitherto tried. 



This engine, the framework of Avhich Avas principally built at the 

 Navy Yard, was an upright engine of two-feet stroke ; and in order 

 to have facilities for comparative trials and experiments, it was ne- 

 cessary that a double engine should be made, the two parts exactly 

 corresponding. I'wo bars of soft iron, six inches diameter and three 

 feet in length, were the prime movers, and these were balanced by 

 means of connecting rods and cranks upon a fly-wheel shaft. The 

 balance-wheel and shaft together weighed 600 pounds. When 

 this engine was first tried, with the same battery which had before 

 given me one-fifth of a horse power, with a smaller engine, it pro- 

 duced only one-third of a horse power. By careful attention to the 

 adjustments, and particularly to the cut-off^, which was a very dif- 

 ferent thing now from what it had been in smaller engines, the en- 

 gine soon yielded one-horse power. Here was a gain of eighty per 

 cent, as measured merely by the size of the battery. But it was 

 much more; for the cost was found to be less for one-horse power 

 than it had been before for one-fifth of a horse power in a smaller 

 engine ; how much less has not yet been ascertained. 



A great variety of experiments were continued with this engine, 

 to be hereafter detailed, each having a definite object; and, I am 

 happy to say, each resulting advantageously ; so that finally, by little 

 daily increments, I obtained from this engine, by a trifling addition 

 of battery, a full two-horse power. 



By way of giving a practical character to the engine, it was geared 

 to a circular saw ten inches in diameter, the turning lathe and grind- 

 stone of the workshop; all of which it worked simultaneously, as 

 witnessed by a number of visitors, and, if I mistake not, by your 

 predecessor in ofiice, in company with Lieut. Maury, of the Na- 

 tional Observatory. 



After many satisfactory trials with this engine it was taken down, 

 and all its available parts used in the construction of the single hori- 

 zontal engine which I had the honour lately to exhibit before the 

 Smithsonian Institution. This change was made for the purpose of 

 dispensing with the dead weight of one of the driving-bars, and more 

 particularly for introducing the important feature of keeping up the 

 magnetism of the driviug-bar. As soon as this new form was com- 



