New Electro-Magnetic Engine. 133 
helix; for the size of the helix and bar may be increased so 
as to measure the power of any number of combinations. The 
bar in this case has its lower end just within the upper part 
of the helix, and its upper end attached to the hook of the 
spring balances commonly used in shops and elsewhere, for 
weighing light goods, &c. The great power of the helix in 
this case is due to the proportions of its length and diameter, and 
the length of the wire to the quantity and intensity of the cur- 
rent. The helix is about four inches long, three inches diameter, 
central opening three fourths of an inch diameter, and of one 
continuous copper wire, of size No. 16. 
Fig. 1. 
AXIAL RECIPROCATING ENGINE. 
The construction of the engine will be readily understood from 
inspection of fig. 1. a, a’ are two helices of the above description, 
firmly secured to the base board, and set with their axes exactly in 
a straight line. The two bars, 8, b’, connected together by a stout 
brass rod, are attached to a sliding frame, f, f, and made to play 
with as little friction as possible. The wires from the extremities 
of the helices pass down through the base - Sig, 2 
board, and the proper connexions are made 
with the cut-off upon the shaft of the fly- 
wheel, as shown in the detached figure 2. 
The dotted lines indicate the course of the 
Wires and their connexions with the cups, 
¢, c, and the conducting springs, e, e, fig. 2. 
The operation of the cut-off or electrotome, 
will be readily understood by any one fa- 
miliar with the rotary machines without 
change of poles, which I published several 
