150 
Analyses of Books. 
will be sufficiently obvious to those acquainted with the general principles of such 
physical inquiries. It may be sufficient to state that it has been assumed, as ge- 
nerally received, that air having a bulk of 1 at any temperature l becomes I 375 at 
any temperature 1+ 180°. A very full detail of all the experiments, and of the me- 
thods of calculation, is given in the paper, to which we must now finally refer, and 
conclude with the table of results deduced. 
Average Results. 
Full red heat. 
Orange Heat, 
Silver melts, 
5.. 1 G. 
5.. 25 G. 
1200 * 
1650 
1830* Daniel 2233* Wedgewood 4777’ 
1920 
2050 
VI. On Captain Parry's and Lieutenant Forster's experiments on the velocity 
of sound. By Dr. Gerard Moll, Prof. Nat. Ph. University Utrecht , communi- 
cated by Captain Henry Kater, V. P. R. S. 
It has been long known, that Newton's expression for the velocity of sound 
does not agree with observation. For while the former gives the velocity about 
980 feet in the second, the latter shows it to he nearly 1100. Laplace has en- 
deavoured to improve the formula, by introducing a coefficient having reference to 
the elasticity developed by the latent heat which is set free at each undulation of 
the air, by its consequent condensation. Tue value of this coefficient has been taken 
from the experiments of Messrs Gay Lussac and Welter. Even with this 
correction, experiment and theory differ 4 to 0 metres or 13 to I!) l’eet. This dif- 
ference has been attributed, partly to the uncertainty of the above coefficient, partly 
to the errors of experiment. 
The object of the present paper is to show, that the latter error can in no way he 
considered to account for this difference, and that the source of the error, if not in 
the uncertainty of the coefficient, the value of which is derived from M. Gay 
Lussac and Welter's experiments, must be sought elsewhere-(-. Dr. Moll had, 
in concert with Dr. Overbeck, carried on a series of the most elaborate experi- 
ments on this subject yet performed, an account of which was published in the Ph. 
Trans, for 1824. — Captain Parry and Mr. Forster had also conducted a series 
of similar experiments at Port Bowen, in lat 73' 13' 39". On reducing the results 
of each series to the same conditions of gravity of pressure and temperature, he finds 
the following values established, as the number of metres travelled by sound in 1 
second of time. 
Metre 
Captain Parry and Lieut. Forster, 4th June, 1825, 333. 15 
Do. Do. 17th and 21st February, 1825, 333. 71 
Do. Do, 22d March, and 3d June, 332. 85 
Dr. Moll and Dr. Van JBeek’s, 332. 05 
Consequently the difference amongst experiments, conducted under such very 
different circumstances, is here much less than the discrepancy of theory and ob- 
servation. 
The following results may also he compared. 
Messrs. Stampfer and Von Myrbach, in 1822, 333.25 
MM. Arago, Mathieu, and Biot, 331.05 
M. Benzenberg, in Germany, 333.7 
MM. Epinoza and Bauzain Chili, 356.14 
Dr. Olinthus Gregory, in England, 335.14 
The French Academicians, in 1738, 332.93 
* Guyton Morveau (Ann. de Ch.)gives 1822°, 7. His pyrometer was a bar of pla- 
tina, the expansion of which was measured by a multiplying index. The melting 
point of gold helixes at 2517° 6. 
+ In a very ingenious paper by a Mr. Mcikle, in a late number of Brewster's 
Journal, it is remarked, that while philosophers have affected to correct for the in- 
crease of elasticity, occasioned by the liberated caloric in the condensation of tbs 
pulses, they have altogether neglected the larger and more obvious source of error, 
occasioned by the increase of elasticity due to the heat liberated by the firing of tbs 
gunpowder. 3 6 
