Description of the model of an Electro-Magnetic Engine. 313 
may be considered as similar to that of a number of wires wound 
in the same direction, whose surface is equal to that of the ribbon. 
The labor of constructing a magnet of any size upon the old plan, 
by winding an iron with a number of wires, is very great, but a mag- 
net constructed upon the plan mentioned above may be made in a, 
few hours. 
The expense of construction is also vastly diminished, and this, 
not only by diminishing the labor, but also the cost of materials. 
And as the power of the magnet may be increased to an unlimited 
extent, it must be preferable i in every respect to those constructed 
with wires. 
Arr. XI. —Deseription of the model of an Electro-Magnetic En- 
gine, constructed by Joun B. Zasnisxie, M.D. 
Tue facility with which the poles of an electro-dynamic magnet 
may be changed by reversing the electric current passing around it, 
first suggested the construction of electro-magnetic engines. The 
first apparatus constructed upon this principle was made by Prof. 
Henry, who gave a vibratory motion toa magnet to which were at- 
tached two bent wires alternately dipping in two cups of mercury on 
each side. 
Some time since I constructed a model of an engine upon this 
principle, of which the following is a description. 
A, B, is a large compound magnet, composed of sixteen bars of 
steel, each one quarter of an inch in thickness and two poi long, 
magnetized separately, and combined into one magnet. This has 
an alternating motion upon an axis between the poles of two horse 
shoe galvanic magnets, constructed upon the principle mentioned in 
the preceding article. 
These magnets CED, F HG, are composed each of a horse 
shoe of soft iron, twenty four inches long, and one inch in diameter, 
wound with a zinc ribbon one inch in width, and one hundred and 
twenty feet long. 
N, is a rod turning a crank which moves the fly-wheel P.O, is 
arod haying two pins projecting from it which moves a lever attach- 
ed to a bascule, which for the sake of distinctness is not represented 
in this figure but may be seen below. ‘This is composed of a piece 
of mahogany pierced with four holes, two of which are oblong, and 
> Vou. XXXIT.—No. 2. 
