64 ANNUAL OF SCIENTIFIC DISCOVERY. 



France, where great attention has been bestowed upon the per- 

 fecting of these motors, is the apparatus of M. Dnhos, which, 

 with a battery of 70 cups, gives a working power of 2 kilo- 

 grammetres, or one-thirty-eighth of 1 horse-power. The same 

 authority pronounces the next best engine to be that of Loiseau. 

 Tiiis raaciiine, with 12 Bunson's cells, gives only the one- 

 hundred-twenty-seventh of 1 horse-power. An electrical motor 

 exhibited by an Englishman attracted considerable attention 

 at the Paris Exposition. It was worked by a battery of 50 cells, 

 and was warranted of 1 horse-power. When, however, sub- 

 jected to an actual test, it was found to be but the one-hundred- 

 fifty-second of 1 horse-power. 



lilr. Stuart's engine is evidently superior to either of these 

 machines. The principle of its construction has been so highly 

 commended that he is going on to construct larger ones. In its 

 present incipient state, the apparatus may be emploj'ed to ad- 

 yantage in pumping, running sewing-machines, or turning lathes, 

 or other light work. The inventor feels confident that larger 

 engines can be built, with not a proportionate but a far greater 

 increase of power; founding his belief on the fact that doubling 

 the size of the battery much more than doubled its efficiency. 

 The immunity from danger by fire or explosion is a great recom- 

 mendation which this motor enjoys in common with others of its 

 class. The claims for superiority peculiar to this machine are, 

 the arrangement of the magnets, so that a steady and uniform 

 electrical current is kept up, and so that they are only magnetized 

 twice in each revolution, instead of many times, as iii most other 

 motors. — Scientijic American. 



Ericsson's solar engine. 



Mr. C. H. Delamater communicates an article to the *' Scientific 

 American," from which the following are extracts: — 



"Captain Ericsson, at the centennial celebration of the Univer- 

 sity of IiUnd,'in Sweden, last spring, forwarded to that ancient 

 institution an essay showing that solar heat ma}' be so employeti 

 as to furnish a large amount of motive power for practical jjur- 

 poses. 



" I have witnessed the operation of one of Ericsson's solar en- 

 gines, to be actuated by atmospheric air heated by the direct inter- 

 vention of concentrated solar heat. Mechanical readers will be sur- 

 prised on hearing that the working piston of the model engine 

 makes upward of 300 strokes pei- minute. 



"The simplicity and moderate cost of the means devised to con- 

 centrate the solar heat are such that no practical difficulties j)re- 

 sent themselves to prevent the construction of solar engines of 

 any desirable power; the facility with which the radiant heat of 

 the sun ma}' be collected and (concentrated from acres of surf ice, 

 by the means contrived, will alike surprise and interest the me- 

 chanical and commercial community." 



" The following translation of the essential part of Captain 



