NATURAL PHILOSOPHY. 107 



and so far successfully conducted, should be carried at least beyond an 

 uncertain issue, and every important point should be settled, and par- 

 ticularly that of its availability on an extensive scale. The power is 

 peculiarly fitted for purposes of navigation, if it can be made subser- 

 vient ; and a trial upon a scale of one hundred horse-power seems to 

 be the only mode of arriving at a definite conclusion upon this point. 

 It is obvious that, preliminary to such an undertaking, a great many 

 experiments will be absolutely necessary ; and such only as one quite 

 familiar with the difficulties of entering upon an entirely new field of 

 operation can properly appreciate." 



At the exhibition before the Smithsonian Institution, the engine was 

 operated by a battery contained within a space of three cubic feet, the 

 engine and battery \veighing about one ton. When the power was 

 thrown on by motion of a lever, the engine started off magnificently, 

 making one hundred and fourteen strokes per minute ; though \vhen 

 it drove a circular saw ten inches in diameter, sawing up boards an 

 inch and a quarter thick into laths, the engine made but about eighty 

 strokes per minute. 



The force operating upon the magnetic cylinder throughout the 

 whole motion of two feet was stated by Prof. Page to be six hundred 

 pounds when the engine was moving very slowly, but he had not been 

 able to ascertain what the force was when the engine was running at 

 a working speed, though it was considerably less. 



At the American Association, Prof. Page estimated that the cost of 

 one horse-power for twenty-four hours would be about 20 cents ; that 

 is, provided the principle can be made to work for so long a period as 

 twenty-four hours uninterruptedly. He had succeeded in operating a 

 machine of four horse-power three hours, but was as yet dubious of 

 the continued power of the battery, which is liable to attain its maxi- 

 mum at about this period, and then decrease in a similar ratio. Prof. 

 Johnson observed that this estimate was based upon too high a cost for 

 the zinc, and that 10 cents would be a nearer estimate. In either case, 

 a very great advance is made upon all previous experiments. It was 

 also observed, that the cost of electro-magnetic power was not to be 

 reckoned in this comparison by the mere cost of zinc, nor the cost of 

 steam by the pounds of coal consumed. The cost of human life, the 

 sacrifice of millions of property, and the risk of millions more, and all 

 the contingent advantages and disadvantages, were to be taken into ac- 

 count. Prof. Page explains his mode of measuring the power of the 

 engine as follows : The brake was loaded to 620 pounds ; the power 

 required to barely keep the engine in motion under this load was 126 

 pounds. The full power being on, the engine made eighty revolutions 

 per minute under this load. The circumference of the wheel being 

 about four feet, it was easy for any one to compute the horse-power 

 from these data. 



The method pursued by Prof. Page is said to be entirely new and 

 distinct from any hitherto tried. In all former electro-magnetic ma- 

 chines, the power is made up of a series of impulses, while in Page's 

 engine, which he styles an axial engine, the power is uniform and 

 continuous, and it is as easy to make an engine of twenty-four feet 



