418 
SCIENTIFIC INTELLIGENCE. 
=. 
I. CuemistTry AND Puysics. 
- ee ige camer on, &c.; by M. es (Ann. de Chim. 
et de Phys., Feb., 48.)—Previous as perlaidiipe™ ave Meleraitedthe 
amount of setae by thermometers at different distances from the 
ground, the lower thermometer being surrounded by the radiating 
substance. The lower strata of air being cooler than those above, 
reduce the temperature of the lowet thermometer—while the naked 
instrument having itself'a high radiating power, does not Corey indi- 
cate the temperature of the air in which it is place 
os avoid these sources of error, the instruments shoyld be placed at 
level, and that intended to. measure the loner of t 
air should his its radiation reduced toa minimum. As metal foil can- 
not be applied ne ni the bulbs, the author devised hee following 
mode of experimentin 
A sound bottle’cork is pierced with a hole to admit the stem ‘of a 
reba which is fe through until the bulb is within } of an 
inch of the cork. It must then be fastened.with @ little wax and with 
wedges of rok The oon which should be marked upon the tube is 
taken off oma piece of paper and transferred to a thin slip of ivory. 
This is then fastened in a slit in the cork so that it shall coincide 
with the scale on the tube, and secured ‘in its ccs allt end of the 
The instrument thus prepared 5 Nee priv by experiment to be 
almost free from the influence of radiation, and pad ot ree a true 
measure of the temperature of the air—on the other hand a coating 
of lampblack raised the ‘radiation to a maximum. In the use of 
these thermometers, eos were placed » horizontally i in tin vessels, hav- 
ing the form of a truncated cone two inches in diameter below, and 
seven inches above, shou four inches deep, and supported on three 
feet formed by thin"tubés of-sheet tin two feetlong. A hole at the side 
with a short tube to embrace the cork, allowed the introduction of the 
ag its bulb being in the centre of the dish, and at little dis- 
tance from the bottom ; plates of tin served as covers. 
We ‘se been thus particular in describing these instruments, as they 
are decidedly the most suitable for this kind of i investigation, which have 
ever been described. 
Two thermometers furnished with polished caps, “Whed a third with 
one coated with lampblack, were exposed in the tin vessels, — While 
covered, Sr stood atthe same height, but when the covers were re- 
ee m one of the two with polished caps and from the third, the 
at 
‘tent with lampblack) immediately fell, and in ten minutes: 
4 
| alee re Dhcdalale. i a. he a Se 
