328 Mr. Patten’s Air Pump. 
which the air pump can be immediately converted into a 
_ condenser; the construction of the stop-cock is, | appre- 
own contrivances yet there are other gentlemen who perhaps 
may differ from Mr. P. in opinion on this subject ; but after 
all, the merits or demerits of the proposed improvement 
must rest, not on opinion, but on its practical utthty, and 
yon that I am entirely willing that it should stand or fall. 
er aa something similar to this may have been suggested 
before ; there have been numerous inventions to dispense 
with alison; and the contrivance may have been thrown 
ade as useless, thus sharing the fate of many mercurial air 
ayes 
‘Ato the fie pei charge of borrowing,” famnot conscious 
of having made that insinuation myself, but I am conscious 
that none was ever intended by me, as f am determined that 
my remarks shall ever be governed by courtesy and candour. 
It does not diminish the credit of Scheele that, without 
any knowledge of what had been done, he shoul d have dis- 
covered oxygen gas after its discovery by Prie ao and, 
arvis componere magna,” it is not, perhaps, disreputable 
to me, without any communication, directly or indirectly, 
with Mr. P., to have entertained notions about an air pump 
similar to his own, even “several months,” or ‘“ several 
years,” after he had conceived them; nor ‘does it, 1 con- 
ceive, diminish aught of the praise to which Mr. P. is entitled, 
that another individual should have had similar notions to 
those he possessed. 
soon as the practicability of Mr. Patten’s air pump 1s 
established, I shall endeavour to avail myself of its use, and, 
whether furnished or not with the “ awkward alteration,” 
Gracie: cheerfully give him the whole credit to which he is 
titled. 
There is certainly nothing remarkable in the fact that two 
persons, “‘at no inconsiderable distance from each other,” 
having the same olyect in view, should adopt similar means 
for attaining it. There are not wanting insiances of per- 
sons, living in different countries, and at different periods of 
time, attaining the same object by similar methods, and that 
100 without any concert, or any knowledge of a prior inven- 
‘ton; this last remark is probably applicable to the “ balance 
