268 
Cl’s Answer to P. 
[Sept, 
mountain have not retained their full proportion.” His analysis gives carbonic 
acid 51,627, magnesia 47,566. But this is the very composition of carbonate of 
magnesia, according to Berzelius, whose numbers are 51,69 and 48,31, and of the 
accuracy of these niy own experiments do not permit me to doubt. The views gene- 
rally received on the subject of definite proportions do not warrant such a supposi- 
tion as Dr. Thomson’s. 
Sir, 
VI. Cl’s Answer to P. 
To the Editor of Gleanings in Science. 
I have read with considerable interest the paper of P. in your 8tli number “On 
the Measure of Labour in India.” The writer well supports the cause he has un- 
dertaken, and I fully subscribe to all his deductions, which are indeed undeniable. 
One only remark have I to offer, that he mistakes the purport of my letter 
altogether, in deeming me a blind advocate of machinery versus labour. It was a 
suspicion that the method in question did not do justice to the labour employed on 
h> — that it gave a less result than the same quantity of labour employed in another 
manner which induced me to notice the subject; and it will be observed, that I stated 
the question hypothetically , as not advancing it on my own knowledge. My words are : 
“ The difference here is enormous, and, if real, is certainly worth pointing out." And 
again, “ 4n arrangement that will not permit six average Bengalees to do the work,” 
&c. Here, it is evident that it is the arrangement which is supposed objectionable, 
and it is by no means inferred that six natives cannot do the work of one European. 
On the contrary, the arrangement is pronounced vicious that occasions so preposte- 
rous a result. 
The difference however P. asserts is not real ; the quantity raised by Professor 
Robison’s pump being in his opinion purely imaginary. To this I can only answer 
that prima facie it-does appear exceedingly unlikely, that Professor Robison should 
have advanced a statement of this kind without sufficient grounds. To gain what 
light I could on the subject I referred to the work quoted in your second number; 
and as it will better enable your readers to judge for themselves, I shall here tran- 
scribe the passage at full length. 
' “ One great excellence of this pump is, that it is perfectly free from all the defi- 
ciencies which in common pumps result from wantofbeiug airtight. Another is, 
that the quantity of the water raised is precisely equal to the power expended; for 
any want of accuracy in the work, while it occasions a diminution of the quantity 
of water discharged, makes an equal diminution in the weight which is necessary 
toi pushing down the plunger. We have seen a machine consisting of two such 
pumps suspended from the arms of a long beam, the upper side of which was form- 
ed into a walk with a rail on each side. A man stood on one end till it got to the 
bottom, and then walked soberly up to the other end, the inclination being about 
twenty -tire degrees at first, hut gradually diminished as he went along, and changed 
the load of the beam. By this means he made the other end go to the bottom, and 
so on alternately, with the easiest of all exertions, and what we are most fitted for 
by our structure. W ith this machine, a very feeble old man, weighing 110 pounds, 
raised 7 cubm feet of water 1 4 feet high in a minute, and continued worldrig S or 
10 lours every day. A stout young man, weighing nearly 135 pounds, raised 8j 
o the same height ; and when he earned 30 pounds conveniently slung about him, 
he raised 9, fee., to this height, working 10 hours a-day without fatiguing himself. 
nrnnrSf CCdS f?f ' l f “ ax “ luul ot a hogshead 10 feet high in a minute, in the 
proportion of 9 to 7 nearly.” * 
, is T ,iu ' decisive of the question, if we allow Professor Robison 
I confess Tio ! witness. Anil why his authority should be inferior to Coulomb's, 
misled bttl,e i n t ° S Tu r ' our ^respondent,” says ft, “ ,„ u , t n0 doubt have been 
b l d Qf I , rof ” r Rob,s(m s l ,nm P ; for, if they are correctly slated, the 
henchmen W» r “ 1Sed 3000 ,“ ls 11 Hi an<i filr deeded all that the strongest 
k s t ou t vounr- „ , edectcd. What will lie say then to. the performance of the 
for me Iran nnui an W i th 3l)Ib ’ which is to nearly 5000 uiaumlsr As 
noiiSnvout” b rCpC what I saul before, “that the difference, if real, is worth 
raLed 10 feet i„ L l>l "' arS H Desa S uber ’ s determination (1 hogshead of water 
“ W ho si a R dee-4 1 “T 1 is , ^valent '» "hout 4000 mat,, ids. ° 
Robison ami De«» "’ hen , d ° c ' 0Ri disagree?” We have here Coulomb verms 
Robison and Desaguliers , and how, except by trial, we are to determine which is 
