438 the batteries TRIED IN O’SHAUGHNESSY’S EXPERIMENT. 
the raaximTam forces are exerted in succession 
from right to left, at an interval of half an 
inch and in an ascending plane. 1 hus the 
two inch distance or interval between the 
magnets is (with reference to the entire series 
of wheels considered as a revolving cylindor 
or drum) i educed practically to a halt inch^ — 
or, in other words, if a diagonal line be drawn 
from the magnet in the horizontal plane on 
the right, to ihat 30 degrees above the horizon 
on the left, in each ascending half inch of this 
diagonal there isa magnet constantly exerting 
its maximum po\ver. 
From this arrangement I anticipate the 
most favorable results. I see no reason why 
it should not answer. Should it prove suc- 
cessful, the applicability of the electro-magnet 
as a locomotive working power will cease to 
be a matter of speculation. 
The application of this power to locomotive 
engines on railroads is the first which I anti- 
cipate. 'I'he recent treatise on locomotive 
machines by the Chevalier de Pambnur 
makes me speak wdthsome confidence on this 
point- His admir.ihle investigations on the 
theory and working force of t.ie carriages on 
the Manchester and Darlington railways, 
shews that the I'ower necessary for the 
pulling of one ton at the average is actually 
only 'Zi lbs ! — that is, that a weight of seven 
pounds suspended over a pulley by a cord 
attached to the carriage wiP draw the ton 
weight on a level railway. My first model is 
by experiment proved to possess one-seventh 
of this power — or, in other words, to have a 
tractive force sufficient to move more than 
3Q0 lbs. Now the weight of the model iiself 
was but 12 Ihs. its batteries 60 ; and trivial 
as is this weight, there are numerous facts 
which shew that it may be very much 
reduced. The magnets may be all holJow for 
instance, as I inferred from iMr. Barlow’s 
experiments and verified by my own, on 
magnets made from gun barrels. Acain, the 
most po werful oftheelectro-magne's hitherto 
made, viz. the American one, which support- 
ed a ton, only w^eighed 27 lbs. 
Numerous facts, too, seem to indicate that 
the size of the galvanic battery may be re- 
duced to very insignificant dimensions. The 
magnet now exhibiting in the Adelaide Gal- 
lery in London, and which sustains 300 lbs. 
weight, is rendered active by a set of plates 
which fit in a pint vessel ; and one belong- 
ing to Mr. Marsh ot Woolwich, which sup- 
ports 500 lbs. is excited by a battery contain- 
ed in a half pint mug. Professor Moll of 
Utrecht has made a ‘2ob lbs. m gnet. which 
has only a single galvanic disk one inchin 
diameter. These facts are extremely en- 
couraging, though their applications to the 
object now in view can only be made with 
great caution. At first sight, it migh; natur- 
ally appear that the sustaining power of a 
magnet would be a just measure of its avail- 
able force ; but I have found by repeated 
trials that very good sustaining magnets may 
be inferior in moving influence to magnets of 
far less sustaining attraction. I have found 
with my models that the longer the distance 
from which an electro- magnet attracts a 
small piece of steel, the better is its working ! 
power ; and in partial conformity with facts ! 
recently announced by Professor Ritchie, I I 
have found that the length of the attracting * 
di-tance is increased by prolonging the legs ' 
of the electro-magnet. But this only holds | 
good within narrow limits 1 had, for in- 
stance, three magnets made from one bar of 
iron. No. 1 was three inches ; 2, ten inches ; 
3, three feet long, — all were xvound with single 
spirals, and each excited by one Wollaston’s 
though. The magnet No. 2 far exceeded all 
the others in distant attractive power. 
The appropriate batteries for these experi- 
ments, and some economical considerations 
as to the consumption of acid, zinc, &c., 
require to be cursorily noticed before 1 can 
conclude this paper. 
When r commenced these experiments I 
was impressed with the idea derived from the 
hooks i had consulted on the subject, that 
a single pair of copper and zinc plates of 
moderately large size were the best suited for 
the production of electro-magnetic forces. I 
soon, however, found ample leason to alter 
my opinion. I have made most extensive 
trials of a great number of batteries of diffi-r- 
ent kinds, and with tlie results I shall pre- 
sently detail,— premising, tliat the same kind 
of acid was used in each. 
The principal batteries tried were — 
I. Siiirveuii’s cniu ciiii ic copper and zinr cy liii- 
dei s, So lunch fsieemed as magnetic exciters. 
3. A fine single i)l te cell, lielongiiig to Mr. 
Piiiisep. IJ feet wide, by 2 feet long, 
3. All excellent pile of lOO 3 inch plates, beloin;- 
liio to the Medical College. 
4 A Cl nickshaiik’s fifu -plate S inrii iroiigh. I 
5. Ditto, ten plate 4-iiich iiouglisiii porcelain 
cell.s. 
6. Wollaston’s ten-plate 4-inch tionghs, double 
coppers. 
7. Six of Professor Paradny’s rerentiv enn- 
sirncied plates; see Philosopliical Transactions for 
1831. 
8. Professor Daniel’s new battery of cans and 
zinc cytiiidei.s, uiili animal rnembiane interposed, 
Willi sulpliaie of copper solution and dilute sui- 
phuiic acid. 
9. A modification of llie aliove of my own con- 
struction, in i.roiii pssi ve sizes of 1,2,3, &c. to 20 
square indies of copper siuface, the zinc cylinders 
aiiialgaiiiated. 
10. A laiee spiral of ten feet of copper jiy two 
feet, wound l onnd a i)!ate of rolled zinc. 
II. A Wollaston’s ilouhle plate, four inches 
square- 
12. A small spiral, 12 inches by 2, of annealed 
copper and sheet lead 
13. A Wollaston’s plate one inch and half long 
by one hiond. 
The effects of all these batteries were observed 
on the same electro-magnet viz., that used ai 
the exteinal magnet in the first model. 
