428 Scientific Intelligence. 
39°-176, which agrees nearly with the above result. But other results 
show considerable discrepancy ; e. g., Hallstrom, 39°°38, Blagden and 
Gilpin, 39°, Hope, 39°'5, Deluc, 41°, Lefebvre Gineau, 40°, Dalton, 
38°, Rumford, 38°8, Muncke, 38°°804, Stampfer, 38°°75 F. The 
mean of all these observations, is 399-24. 
f anew and practical form of Voltaic Battery of the highest 
powers, in which Potassium forms the positive element ; by Joun Goop- 
MAN, Esq. Communicated by S. Hunter Christie, Esq.. A-M., Sec. 
R.S., (Royal Soc., Jan. 11; Phil. Mag., Feb., 1847, xxx, 127.)—The 
author succeeded in constructing a voltaic arrangement of some power 
by fixi 
tery acted with energy on the galvanometer, and effected the decom- 
position of water. A series of twelve pairs of similar plates exhibited 
a sensible attraction of a slip of gold leaf. Thus it appears that the 
substance which possesses the highest chemical affinity manifests also 
the greatest power of electrical tension. 
18. On Photographic Self-Registering Meteorological and Magneti- 
cal Instruments ; by Francis Ronarps, Esq., F.R.S., &c., (Royal Soe., 
Jan. 21; Phil. Mag., Feb., 1847, xxx, 127.)—The apparatus employed 
by the author at the Kew Observatory, and which he terms the Photo- 
Electrograph, is described by him in the following words :—* A rec- 
tangular box, about sixteen inches long and three square, constitutes the 
part usually called the body of a kind of lucernal microscope. A vol 
taic electrometer (properly insulated, and in communication with an 
atmospheric conductor) is suspended within the microscope, through an 
aperture in the upper side, and near to the object end. ‘That end itself 
is closed by a plane of glass, when daylight is used, and by condensing 
lenses, when a common Argand lamp is employed. In either case an 
abundance of light is thrown into the microscope. Between the elec- 
trometer and the ether, or eye-end of the microscope, fine achromatic 
lenses are placed, which have the double effect of condensing the light 
upon a little screen, situated at that eye-end, and of projecting a strong 
image of the electrometer, in deep oscuro, upon it. Through the sereen 
a very narrow slit, of proper curvature, is cut, (the chord of the are 
being ia a horizontal position,) and it is fitted into the back of a case, 
about two-and-a-half feet long, which case is fixed to the ¢ mig 
the microscope, at right angles with its axis, and vertically. Within 
the case is suspended a frame, provided with a rabbet, into which two 
plates of pure thin glass can be dropped, and brought into close contact 
by means of six little bolts and nuts. is frame can be removed at 
pleasure from a line, by which it is suspended, and the line, afier pass- 
ing through a small aperture (stopped with grease) cut through the 
upper end of the long case, is attached to a pulley (about four inches 
in diameter) fixed, with capacity of adjustment, on the hour arbor 0! @ 
good clock. Lastly, counterpoises, rollers, springs, and a straight ruler 
are employed for ensuring accurate rectilineal sliding of the frame 
when the clock is set in motion. 
