HINTS OF INFORMATION ON THF CULTIVATION OF COTTON. 433 
in their qualifications to reduce, to a suitat le 
foim for publication, tire results of their ex- 
perience, J o all such, the wiiler of these 
menioiand I offeis his assistance, and, in the, 
hope of more rapidly extending our knowledge 
of cotton cultui e, as svell as forwarding the 
wishes of government in the iniproveiiient of 
our commerce, will, willi pleasure, charge 
himself with the task of correcting for pul)li- 
cation, all really practical communications 
tiiat may be addressed to liim. 
The following are some of the points on 
which information is wanted:-— What is the 
depth to which the soil should be turned, by 
ploughing or digging, for cotton cultivation? 
What are the advantages or disadvantages of 
sowdng in rows as compared with broad cast 1 
Would sowing during the earlier periods of 
the rainy season, be productive of larger crops, 
oi improve the staple of the cotton? What 
are the effects ofciopjung the top shoots about 
the time of flowering? In Spain, and the Is- 
lands of tlie Meditei raneao, where cotton has 
been long cultivated, and generally in America, 
the ground is turned to tlie depth of ten or 
twelve inches or more, in iliis country, rarely 
to half that depth. In these countries the 
rovv system is usually adopted, and a regular 
interchange ofseed practised, it being observed, 
that the crops deteriorate both in quantity 
and quality, when tiiis is neglected. In this 
couniry both practices are almost unknown. 
The question of the best time for sowing is a 
local one of season, and must be determined 
by comparative trials, made in the same field, 
and on plants placed, in every otlier respect, 
in the same circumstances. That of cropping 
must, in like manner, be determined by com- 
parative experiments on plants placed, in 
every respect, in similar circumstances. With 
respect to this operation, I may repeat that, 
as the object of it is to retard the two rapid 
flow of the sap, and favour the concentration 
of the secretions on which the formation of 
flowers and fruit depends, it is essential to its 
success, that it be done in verydiy weather, 
and on clear days (exposure to bright sun- 
shine prevents bleeding) ; consequently the 
state of the weaflier should be noted, in con- 
nection with details of experiments illustrative 
of this branch of the enquiry.” 
This is a valuable paper, and we shall refer 
to it again. 
Art. V. — On the employment of the 
Electro-Magnet as a moving power : 
with a description of a model machine 
worked by this agent. By W. B. 
O’Shaughnessy, m. d. — Quarterly 
Journal of the Calcutta Medical and 
Physical Society, Janu'iry, 1837- 
We have already alluded to the produc- 
duction of motion by magneto-electricity, 
and to mechanical contrivances by which a 
body might be made to move continuously 
by magneto-electric agency, and to the con- 
trivance of Dr. O’Shaughnessy exhibited 
at the Government House in November last ; 
the results of which our zealous professor has 
published, strange to say, in a work that will 
be read but by few. To rescue the meri- 
torious exertions of our friend from being 
buried in oblivion, and to spread far and 
wide every invention tending to promote 
useful and important results, we shall 
again curtail otlier leview^s this month in 
order to give the paper in full. 
“In the present and a succeeding paper I 
propose to give an account of some experi- 
ments I recently instituted with the view to 
apply the force of the Electro-Magnet as a 
practical working power. As there are seve- 
ral members of the Society to whom electro- 
magnetic phenomena are but little familiar, 
I will in the first place briefly touch on such 
of the facts previously established in this 
science, as are essential to the comprehension 
of the experiments and models i shall subse- 
quently describe. 
The leading fact connected with the pre- 
sent object, is the magnetic effect produced 
by electricity in motion through galvanic 
conductors. Let a plate of copper and ano- 
ther of zinc, not touching each other, be 
immersed in water acidulated with sulphuric 
or nitric acid, and then let a wire be made to 
touch both plates out of the fluid : the wire 
becomes magnetic itself, and, if placed at 
right angles to a bar of iron, renders the 
iron a magnet also. If the wire be removed 
from either plate, the electric circuit being 
thus broken, the magnetic effects instantane- 
ously cease, and both wire and iron regain 
their oi’iginal neutrality. In conformity with 
this principle, if we take a copper wire cover- 
ed with silk, and wind it in a close spiral 
coil round a bar of soft iron, and then bring 
each end of the wire into contact with the 
copper and zinc plates, the galvanic current 
flows at right angles to the bar through the 
spiral coil, (the covering of silk preventing 
any lateral communication) and the bar be- 
comes a powerful magnet. If swung so as 
to move freely it places itself in the magnetic 
meridian N. and k Its ends are strongly 
polar, N and S. respectively: it attracts 
iron and the dissimilar poles of other magnets 
with great power. If instead of using a bar 
we employ a piece of iron bent like a horse- 
shoe, with the terminating surfaces ground 
and polished, a powerful magnet is obtained, 
which will support a great weight, while the 
spiral is traversed by the galvanic current. 
Several very powerful temporary or electro- 
magnets of this kind, have been constructed 
by various experimentalists. The most 
remarkable is that made in America at the 
Albany College, which supported nearly a 
ton weight. Mr. Marsh of Woolwich has one 
the legs of which are but six inches long by 
one and a half square, which supports 500 lbs. 
