Mr Perkins on the compression of Water and other Fluids. £67 



I cannot pass without notice. Mr Christie says I have in- 

 accurately represented him to have included his chapter on 

 rapid rotations in his original communication, it having been 

 added afterwards. This may be ; but it is all printed under 

 one title, without mark or distinction, and it was impossible 

 for me to know when it was sent. Still, however, if he did not 

 intend it to be so printed, the explanation is so far good, al- 

 though it does not account for the omission of my name. 

 Again, he says it is not quite accurate to say that his hypo- 

 thesis is founded on a comparison of my results, it having 

 been suggested by one only of my leading facts. As Mr Chris- 

 tie knows best, let this also be granted. T only supposed that 

 he would have compared my results to ascertain that the fact 

 was correctly deduced. 



I have no objection, of course, to these verbal corrections 

 being made in my former letter, if Mr Christie imagines that 

 his argument can derive support from such minute distinctions. 



I remain, Dear Sir, Yours very truly, 



Peter Barlow. 



Art. XX. — On the Progressive Compression of Water with 

 High Degrees of Force, with some Trials of its effects on 

 other Fluids. By J. Perkins, Esq. 



The instrument with which Mr Perkins made the experiments 

 of which we propose to give an account, was constructed with 

 much care and attention, and is described with great minute- 

 ness in the Philosophical Transactions for 1826, p. 541. The 

 water was placed in a glass piezometer, consisting of an elon- 

 gated bulb nearly four inches long, and about three-fourths of 

 an inch in diameter, and terminating in a tube of regular bore 

 nine inches long, and about one-eighth of an inch of internal 

 diameter. By weighing the quantity of quicksilver contained 

 in this instrument when full, and ascertaining the weight con- 

 tained in a given length of the tube above, it was found that 

 the whole content was equal to a tube of 190 inches long, 

 having the diameter of the contracted part of the piezometer. 

 In the bottom of the piezometer is a small disk of steel, and 

 above it a delicate hair spring of sufficient strength to retain 



