TRANSACTIONS OF THE SECTIONS. 27 
a great and deserved success of manufacturers, attention could freely be turned to 
experiments on speed, as entered upon by Messrs. Jenkin and Varley; and he men- 
tioned that applications had been made to Government from the first authorities to 
take advantage of the Malta-Alexandria Telegraph for the purpose. 
On an Experimental Determination of the Absolute Quantity of Electric Charge 
on Condensers. By Dr. EssrnBacu, 
This quantity having first been approximately ascertained by Faraday, had been 
afterwards established by the researches of Weber, Thomson, and Joule; but the 
application of these results to submarine cables requiring intermediate reductions, 
the author undertook a direct determination, for which the means had since become 
available. 
A cable of certain description was charged (and discharged) by 100 Daniell’s 
400,000 times in 14" 30’; this quantity of electricity deposited in four several 
yoltameters 12-9 mer. of silver. ‘The determination was repeated under different 
conditions, The absolute quantity can hence be calculated for any other cable by 
means of the well-known formula for determining their relative capacities. The 
quantity of charge on the whole Malta-Alexandria cable by 20 cells (the ordinary 
speaking power) is accordingly equivalent to 0-013 mgr. of silver, a quantity which 
is furnished in 0-964 second by the battery in a closed circuit of 2500 units (one 
Daniell by 1000 mercury units depositing 4:01 mgr. of silver per hour), This 
would therefore be the maximum speed with this battery, as far as merely the 
quantity of electricity is concerned. During the investigation of the method which 
receded the experiment, Dr. Esselbach found the charge and discharge influenced 
fy the resistance to sufficient extent to admit of verifying experimentally the 
second case of Professor Thomson’s theory of discharge, which is of practical import 
ance for the question of velocity. 
Account of an Electromotive Engine. By G. M. Guy. 
The author explained the difficulty of obtaining, by any of the methods hereto- 
fore suggested, a sufficiently rapid motion within the small spaces through which 
magnets or electro-magnets acted with sufficient energy, and chiefly in consequence 
of the rapid diminution of that energy as the distance of the poles increased, even 
by very minute quantities, He exhibited and explained to the Section a working 
model of the engine. 
METEOROLOGY. 
Suggestions on Balloon Navigation. By Isaac Asun, M.B. 
The author ae a a simple contrivance by means of which the opening of the 
escape-valve should depend, when desirable, on the relaxation of voluntary exertion 
on the part of the aéronaut, so that in the event of insensibility supervening at great 
altitudes, the valve should open spontaneously by means of a weight attached to 
its rope, thus causing a descent of the balloon to safer altitudes, and obviating the 
danger to life incurred by Messrs. Glaisher and Coxwell during their recent scien- 
tific ascent from Wolverhampton in consequence of their becoming insensible. 
Dr. Ashe also proposed the adaptation of screw propulsion to balloons, suggesting 
a very light screw, capable of being elevated and depressed through an angle of 
about 150°, so as to be capable of being hoisted while the balloon should be on the 
ground, of being used horizontally as a propeller, or vertically underneath the car to 
cause a temporary ascent, as for the purpose of crossing a mountain-range without 
loss of ballast, which would involve remaining at the elevation so gained, or, on the 
other hand, by reversing the action of the screw, to effect a descent without loss of 
gas. Such a screw he considered could be worked at small elevations (2000 feet) by 
the exertions of the aéronaut ; and its advantages would consist in the conferring, to 
