406 Progress in Science. [July, 
allow a sufficient aperture for illuminating the microscope. The white lining 
is covered with glass, so that the smoke of the lamp cannot blacken it. Small 
as the reservoir appears to be, it contains oil enough to last four hours. The 
means taken to prevent leakage are very ingenious; a carefully-fitted screw- 
cap prevents leakage at the burner, but the greatest ingenuity is displayed in 
fitting the pinion, which raises the wick to prevent escape of oil. So effectual 
are the precautions taken to keep in the oil, that the writer received the lamp 
by carrier, and has since carried it inverted in his pocket, without the slightest 
inconvenience from leakage. The flame can be adjusted at any level from 
about 4to 1z2in. The general form of the lamp can be easily understood 
from the accompanying woodcuts. 
Heat.—Under the supervision of Dr. R. Carter Moffat, a large party of 
gentlemen connected with shipping and the Board of Trade recently assembled 
at Greenhithe, near Gravesend, to witness the power of Paton and Harris’s 
Pyroletor to extinguish fire in closed places. The pyroleter consists of a 
small double pump worked by hand, which sucks up from tubes on either side 
of it strong muriatic acid and a solution of bicarbonate of soda, which 
commingle in a generator forming part of the pump, and the carbonic acid 
gas and solution of salt pass at once down a metal pipe to the hold, along 
whose keelson runs a perforated wooden box which admits of the gas passing 
through to the burning material. The agent, therefore, for the extinction of 
fire is dry carbonic acid gas, which has no action on cargo. A. steamer 
conveyed the party from Blackwall to Greenhithe, where a large wooden 
barge had been prepared for the experiments. Its entire hold was covered to 
a depth of several feet with wood shavings, cotton-waste saturated with 
turpentine, and naphtha. A temporarily-raised and by no means air-tight 
wooden deck, with loosely-fitting boards, formed the wide hatchway covering. 
After the apparatus had been explained by Dr. Moffat, the pipes to the 
chemicals were attached, and the signal given to set fire to the inflammable 
materials in the hold. Immediately the flames ran along the entire cargo 
and issued above the temporary deck, which was then covered with board- 
ing. The pyroletor having been brought into action, and although nearly half 
a gale of wind was blowing, the fire was completely extinguished in four 
minutes. The experiments were so completely successful, and the efficiency 
of the apparatus so apparent, that the party at once agreed to sign a 
memorial to ask Government to compel all long-passage ships conveying 
passengers and cargo to carry one of these instruments. It is computed that 
a 1200-ton ship requires about half aton of each of the chemicals, which, 
with their packages, cost about £20. 
ELEcTRICITY.—From a report by Count du Moncel on the thermo-electric 
battery of M. Clamond we gather that, in this battery the electro-positive 
element is of iron, and the negative element an alloy of antimony and zinc: 
and, as in the arrangement of Mr. Farmer, the elements are connected circu- 
larly for intensity, forming a kind of crowns, isolated from each other by plates 
of amianthus, and having their polar extremities placed in connection with a 
commutator, fixed tangentially to the cylindrical surface of the apparatus, 
and contrived so as to cause these crowns to be grouped either for inten- 
sity or for quantity, as may be requisite. The apparatus has been employed 
for six months at the galvano-plastic works of M. Goupil at Asniéres. The 
gas consumed amounts to 2} frs. per kilo. of copper deposited. 
M. J. Morin has invented a new electro-medical galvanoscope. According 
to the description in the Comptes Rendus it consists of an ordinary two-branch 
electro-magnet, placed vertically, the breach being in the air. A magnetic 
needle is suspended by one of its poles over the breach, through which it pene- 
trates by means of alarge hole. The lower free pole of the needle descends 
as far as the level of the lower part of the ele&tro-magnet’s helices, between 
which it is able to oscillate. The needle is long enough to penetrate the 
breach to the height of its neutral point, thus nullifying at that spot all recip- 
rocal aGion. On making a current circulate in the helices the two poles act 
