2 Electro-Magnetic Machine. 
statements of successful experiments at the late meeting at Bristol. 
Mr. Sturgeon, of Woolwich, England, also reports a galvanic ma- 
chine as being in use on his premises for pumping water, and for 
other mechanical purposes.* 
But, I believe that Mr. Davenport, named at the head of this no- 
tice, has been more successful than any other person in the dis- 
coveryt of a galvanic machine of great simplicity and efficiency. 
During the last two or three years, much has been said of this dis- 
covery in the newspapers, and itis probable, that in a future number 
of this Journal, drawings and an accurate description of the machine 
may be given. Having been recently invited to examine a working 
model, in two varieties of form, and to report the result, I shall now 
attempt nothing more than a see description, such as may render 
intelligible the account I am to giv 
1. The Rotary Machine, poate, of revolving electro-magnets, 
with ficed permanent magnets. 
This machine was brought to New Haven March 16, 1837, by 
Mr. Israel Slade, of Troy, N. Y., and by him set in motion for my 
exainiuation. The moving part is composed of two iron bars placed — 
and 
iy, each other at right angles. They are both 
five and a half inches long, and they are terminated at each end by 
a segment of a circle made of soft iron; these segments are each 
three inches long in the chord line, and their position, as they are 
suspended upon the énds of the iron bars, is horizontal. 
This iron cross is sustained by a vertical axis, standing with its 
pivot in a socket, and admitting of easy rotation. ‘The iron cross 
bars are wound with copper wire, covered by cotton, and they are 
made to form, at pleasure, a proper connexion with a small circular 
battery, made of concentric cylinders of copper and zinc, which can 
be immersed in a quart of acidulated water. Two semicircles of 
strongly magnetized steel form an entire circle, interrupted only at 
the two opposite poles, and within this circle, which lies horizontally, 
the galvanized iron cross moves in such a manner that its iron seg- 
ments revolve parallel and very near to the magnetic circle, and in the 
same plane. Its axis at its upper end, is fitted by.a horizontal cog- 
wheel to another and larger vertical wheel, to whose horizontal axis, 
a: Annals of Electricity, Magnetism, &e. No.1, Vol. 1. October, 
+ Mr. Davenport appears to have been — the inventor of a method of ap- 
iste to produce rotary moti 
