MisceUanies. 193 



Inclination 13° 13' 0.92'^ 



Logarithm of the eccentricity 9.8759106 



Logarithm of half the great axis 0.5486142 



Mean siderial, diurnal motion 533.4409'^ 



Bib. Univ. Mars, 1833. 



PHYSICS. 



8. JVeW property of elementary electromotors. — Prof. Dal Negro, in 

 experiments, to discover some useful application of the magnetism 

 communicated to iron by electrical currents, was led to examine into 

 the greatest effect which could be obtained from the smallest quantity 

 of zinc. 



By zinc plates of various sizes, commencing with those of an inch 

 surface, and ending with those of one hundred and twenty and one 

 hundred and forty square inches, he magnetised a horse-shoe of iron, 

 wound with a spiral. The effects in each case were noted, and 

 those of the smallest plates examined by the simple galvanometer. 

 From these experiments often repeated, the following results were 

 obtained. 



1. Other things being equal, the most useful effect or the greatest 

 relative force was obtained from the smallest plate of zinc. Relying 

 upon the constancy of this important result, he constructs elementary 

 electromotors of plates of zinc, smaller but never larger than one 

 square inch. 



2. To obtain from a given plate of zinc the greatest absolute effect, 

 divide it into the greatest possible number of parts, and join them 

 (par le has) with copper wire, and arrange them parallel, by tens or 

 twenties at pleasure, so as to form a single system, and plunge them 

 all at the same instant, into a small copper trough, subdivided into as 

 many compartments as there are series of plates, and filled with acid- 

 ulous water. 



3. The effect of a given plate of zinc is increased by a simple change 

 in figure, of the same surface but of a larger perimeter ; e. g. by re- 

 ducing a square zinc plate, containing four square inches, to a rec- 

 tangle of six inches long, and three lines high, the effect is more than 

 doubled. 



4. The increase of the electromotive power depends, for a time, 

 upon that of the perimeter, and the division of the constituent parts of 

 the most oxidable metal, or, which amounts to the same thing, it de- 

 pends upon the sum of simultaneous currents, which take place in 



Vol. XXV.— No. 1. 25 



