264 Hlectro-Magnetic Apparatus and Experiments. 
made of silver, and similar to the one described for the revolving 
armature. ‘There are three conducting: springs tipped with sil- 
ver, one playing upon the whole portion, and two upon the dis- 
sected portion of the cut-of.. 'The connexions of the magnet 
Figure 6. 
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wires with the springs and cups p, n, for battery connexion, are 
made .under the base boards, and are marked by the dotted lines. 
Several of these engines have been made by Mr. Daniel Davis, 
Jr., philosophical instrument maker, of Boston; and are beautiful 
working models. Asa proof that electro-magnetism is suscep- 
tible of useful application where only a small power is wanted, 
a’small engine was made by Mr. Davis in the month of July last, 
by the aid of which, an individual gains fifteen dollars: per day 
by the simple operation of drilling the steel plates for gas burn 
ers. I think this may be considered the first instance in which 
