340 Proceedings of the British Association. 
lieve that more cannot be expected from a mechanical force, 
whose existence has only been known since 1834, when I made 
the first experiment at K6nigsberg, in Prussia, and only succeed- 
ed in lifting a weight of about 20 ounces, by even this electro- 
magnetic power. 
“‘T must on the present occasion, confess frankly that hithertn 
the construction of Gastro inagnetic machines has been regulated 
in a great measure by mere trials ; that even these machines con- 
structed according to the indisputable laws established with re- 
gard to the statical effects of electro-magnets, have been found in- 
efficient, as soon as we came to deal with motion. Being always 
accustomed to proceed in a legitimate manner, and feeling great 
regret at the irregular attempts which were being made every 
where, without any scientific foundation, this state of things ap- 
peared to me so unsatisfactory, that I could not but direct all my 
efforts to ascertain clearly the laws of these remarkable machines. 
I submit the formule relative to these laws, which appear to me 
to recommend themselves as much by their simplicity as by the 
natural manner in which they develope themselves. Let Rt rep- 
resent all the mechanical resistances acting upon the machine, 
and v the uniform velocity with which it moves ; we have tor 
the power or mechanical effect, the expression T= Rv. Let n 
be the number of coils of the helix which covers the rods ; 2 the 
number of the plates of the battery; B the total resistance of 
the galvanic circuit; Ei the electro-motive force ; & a coefficient 
which depends on the arrangement of the bars, the distance of 
the poles, and the quality of the iron; we have then for the max 
- imum of the mechanical effect whiicti will be obtained, the ex- 
— 
2? EP 
Re Te: 
For the velocity, which Sen or to this maximum, 
te a ‘ 
For the resistance acting upon the machine, 
nis 2,2 
III. R= AR? ; 
Lastly for the economic effect, i. e. the duty or the cabauied 
effect divided by the consumption of zinc in a given time, 
E 
IV. O= OE 
