~ 
154 Proceedings of Learned Societies. 
elaftic fluids, under the fame preffure, ex- 
pand equally by-heat; and that for any 
given expanfion of mercury, the cor- 
refponding expanfion of air is propor- 
tionally fomething lefs, the higher the 
temperature.” 
Mr. Banxs concludes, from experi- 
ments made by him, to afcertain the ve- 
locity of air ifluing out of a vefiel in dif- 
ferent circumftances, that a prefiure equal 
to 33 feet of water will expel air out of 
bellows into the atmofphere with a velocity 
of 845 feet per fecond—that one foot, of 
water in depth will produce a velocity of 
1471 feet, and one inch in depth, a velo- 
city of 42 feet per fecond, or 20 miles an 
hour. Hence he fays, a table may 
be conftruéted, fhewing the velocity 
communicated to air by any head of 
water, for which the fellowing propor- 
tion is to be affumed :—** As the fquare- 
root of 6 is to 361.6, fo is the fquare- 
root of any other depth to the velocity 
produced by that depth.” 
“In Mr. WiEL1aM HENRY’s Review of 
Experiments which have been fuppofed 
to difprove the Materiality of Heat, we 
have an account and inveftigations of 
thofe made by Count Rumford and Mr. 
Davy, in oppofition to the doctrine of 
Lavoifier refpecting caloric. Mr. Henry 
then examines the experiments and rea- 
foning of Dr. Crawford on this fubjeét, 
after which he undertakes to offer argu- 
ments in defence of the materiality of 
heat. Taking the generally received de- 
finition of matter, he firft examines how 
far its general chara¢ter applies to the in- 
dividual caloric. He affumes, that it oc- 
cupies fpace, or is extended, becaufe it 
‘enlarges the dimenfions of other bodies; 
and for the fame reafon it is impenetra- 
ble, fince if it could exift, at the fame 
time, in the fame place with other bodies, 
their volume would never be enlarged by 
the addition of heat. And although the 
attraétion of cohefion, or that of gravita- 
tion, have never yet been demenfirated as 
belonging to caloric, yet Mr. Henry 
thinks, that one kind of attraction, viz. 
chemical affinity, may be fairly predicated 
of it, which muft be confidered as a pow- 
erful argument in favour of its materiality. 
His reafons for this opinion are—1. That 
all characters, diftinguifhing caloric when 
feparate, ceafe to be apparent, when it 
has contributed to a-change in other bo- 
dies :—2. The relation oi caloric to dif- 
ferent fubftances appears to obferve the 
laws of fimpie and compound elective 
affinities :—ani 3. It aéts, fometimes, as 
am intermedium in--combining bodies, 
[Sept. ¥, 
which, without its aid, are not fulcepti< 
ble of combination. 
Mr. Joun GoucuH has given a very. 
ingenious paper on the inveftigation of the 
method whereby men judge, by the-ear, 
of the pofition of fonorous bodies relative 
to their own performs. Befides various 
curious difcuffions contained in this paper, 
the author produces faéts and reafons to 
fhew, that the art of the wentriloquift 
confifts principally in intercepting the. 
original found of the voice, and of con- 
veying in its ftead the echo of it only. 
As the found of bells, to a perfon walk- 
ing in a valley obftrufied by buildiags, 
rarely reaches the ear in its true direction, 
but is reflected from different places, and 
by that means performs the part of an ex- 
pert ventriloquit on a theatre; fo Mr. 
Gough concludes, that as in the cafe of 
the bells, the echo reaches the ear, while 
the original found is intercepted by aeci- 
dent, whereas in the cafe of the ventrilo« 
quift it is intercepted _by art. 
The theory of compound founds is in- 
veftigated in another paper by the fame 
author, in which he points out the dif- 
ference of Dr. Young’s theory with re- 
fpeét to the human voice, to that which 
he adopts. According to Dr. Young, 
the voice is a compound by coalefcence 5 
but by Mr..Gough’s theory it is a mix= 
ture of imperfect unifons, which mixture 
appears to be_a fingle found, becaufe it 
has but one direCtion. ‘ 
Dr. Hutt, in his Obfervations on the 
Nervous Syitems of different Animals, &ce. 
&c. refers all animals to two grand clafles ; 
the firft comprehending thofe which have 
vertebra; the fecond, thofe which are 
deftitute of vertebra. The nervous- 
fyftem of the former confifts of brain, 
fpinal-marrow, and nerves, and is com- 
pofed of two princépal fubftances, namely, 
the cortical and medullary: and all ani- 
mals that have vertebrae, have the fame 
number of fenfes as man. 
Animals deftitute of vertebre, he di- 
vides into three orders: the firj? compre- 
hending infe€ts and fome worms, which 
have a brain, {pinal-marrow, and nerves, 
or what at leatt correfpond to thefe: the 
fecond have a brain and nerves, but no 
{pinal-marrow: the third comprehends - 
animals of a gelatinous texture, and that 
have no evident nervous fyfiem, as Po- 
lypes. . 
To fhew the pre-eminence of man over 
other animals, Dr. Huxt points out the 
fuperior magnitude of his- brain in pro- 
portion to the reft of the nervous fyftems 
and obferves, that in the higher orders of 
animals, 
