436 : 
ring, with a temperature of about 844°, in 
the first decade of April, and again in the 
last decade of September. 
Mr. Goldingham has further found, from 
numerous combinations of his obseryations, 
made when the air was calm, that for each 
degree of increase of temperature, 1.2 feet 
may be allowed, in the velocity of sound, 
for a second ; for each degree of the hygro- 
meter towards dampness, 1.4 feet; and for 
each rise of one-tenth of an inch of the 
mercury in the barometer, 9.2 feet. Mak- 
ing these the bases of calculation, he finds 
the mean difference of the velocity, between 
a calm and a moderate breeze of wind, to 
be nearly 10 feet in a second; and by com- 
paring other results together, a difference 
of about 214 feet in a second, or 1275 ina’ 
minute, is found between, the wind being 
in the direction of the motion of sound, or 
opposed to it. : 
; As to the recent French observations 
abovementioned, they furnish us only with 
the temperature, which was 343° lower 
than in the East-Indies, when the general 
or Newtonian mean of 1142 feet was ob- 
seryed ; to which, applying Mr. G.’s rule, 
34,5+1.2+1106.3= 1148.7 feet per second, 
would be the French velocity, at 843° of 
Farnh., without taking either barometer 
or hygrometer into the account. An ac- 
count of Dr. Gregory’s very able experi- 
ment has already appeared in our August 
number, page 50. 
The Specific Heat of the Gases has been the 
subject of an elaborate course of experi- 
ments by Mr. W. T. Hayeraft, the parti- 
culars of which have lately appeared in the 
tenth volume of the Transactions of the 
Royal Society of Edinburgh, (see also the 
Phil. Mag., Nos. 317 and 318). The ap- 
paratus used on this occasion is said to 
have been ingeniously contrived and well 
executed ; but the drawing is so bad,* and 
its description so lame and defective, as 
to be with the utmost difficulty under- 
stood: it seems, however, to have been 
used by Mr. H. with great care, and atten- 
tion to accuracy. His results are,—First, 
That the specific heats of all the gases expe- 
rimented upon, are to each other, when 
carefully dried, invertly as their specific gra- 
vities ;—Secondly, That aqueous vapour, in 
combination with any gas, increases its ca- 
pacity for heat, probably in the same arith- 
metically increasing ratio as the expansive 
force of the mixture is thereby increased ; 
and,—Thirdly, That the mixed gas expelled 
from the human lungs in respiration, has 
the remarkable property of agreeing with 
atmospheric air in its capacity for heat, ex- 
cept between 95° and 100}° of Farnh. , 
* We netice this circumstance, because of the 
frequent occurrence of plates, in the transactions 
of our learned societies, from drawings, inadequate 
to explain the subjects depicted. We may men- 
tion the engravings of Captain Kater’s admirably 
contrived pendulum apparatus, as in this predica- 
ment. Few, ifany, readers haye been able to un- 
derstand them. : : 
Spirit of Philosophical Discovery. 
[Dee. 4; 
in which. range alone, so essential to the 
supply of animal heat, the specific heat of 
the respired air is less than that inspired ! 
The insensible Causes operative in the Dis- 
solution of Salts, and in Capillary Attraction, 
which hitherto have escaped the observa- 
tion of philosophers, have, by M. Bee- 
querel, lately been referred to electrical 
currents, which he has succeeded in ren- 
dering visible, through the extreme sensi- 
bility of his galyanometer; a number of 
which instruments he can so dispose, that 
each mzy coneur to the general effect of 
augmenting, in an indefinite degree, the 
indications of currents of the electric fluid. 
Comparative Illuminating Power of Gases, 
made from Coal and from Oil.—The over- 
rated estimate of light procurable (accord- 
to several writers) from oil gas as compared - 
. with coal gas, as unity, from 3.0 to 1.8. 
times, by Dr. Fyfe, in our October number, 
p- 337, has been further reduced by Profes- 
sor Leslie to 1.5, in consequence of a’ 
course of comparative’ experiments, ‘by 
means of -his photometer, on the oil-gas 
delivered by Mr. Milne to his customers 
in Edinburgh, and that delivered by the 
Edinburgh coal-gas company. It is, how-— 
ever, remarked by Dr. Fyfe, that, Mr. 
Milne’s apparatus being out of repair, his’ 
gas was, at the period of the professor’s 
experiments, below its usual average qua- 
lity. 
The Adjusting and Ascertaining of the Rates 
of any Number of Chronometers on board of 
Ships lying in a Harbour, may be effected 
with ease, according to a method lately 
pointed out by the Rev. F. Fellows, as fol- 
lows; viz. A spot on the shore should be 
selected, near to and visible from the an-* 
chorage of the ships in harbour ; and there- 
on an observatory should be provided, and : 
furnished with a good clock, and with a- 
transit instrument for its adjustment; or, - 
in place of the latter, a good sextant and 
artificial horizon may suffice. Ina window 
of this observatory, visible from every ship, » 
a powerful Argand’s lamp should be pro- 
vided, and furnished with a shade or shut- 
ter, which can, by means of a wire and 
bell-pull near to the clock, be either drawn 
up or let down, so as instantly to intercept 
and exclude the light of the lamp from the . 
ships.. Then, the clock being .in adjust- 
ment to the mean time of the place, at 
some hour previously agreed on, say one , 
or two hours after sun-set, the lamp being 
previously burning, and the observer watch- 
ing the clock, at the instant the hands in- 
dicate the hour, the shade should be inter- 
posed, and the light hid from the ships for 
the space of a quarter or half a minute: 
then the light should be exhibited again, 
until the instant the hands arrive at five 
minutes, when it should again be obscured 
for a like space, and then exhibited again, : 
until the hands exactly indicate 10m. ; and 
so on, for a longer or shorter period, ” 4 
eac 
