180 Miscellaneous Intelligence. 



temperature = 0.0026 V, and the compression by the weight of the 

 water is consequently =r 0.0005. Assuming that the condensation 

 is proportional to the pressure, we shall find the compression by the 

 weight of the atmosphere = 0.0000027, which is nearly three times 

 as much as 0.000001, the value assigned by Oersted for this com- 

 pression *. 



Note. The great condensation of mercury following from this 

 experiment makes it doubtful, in our opinion, whether some of the 

 oil may not have insinuated itself between the glass and the mercury, 

 and it would, perhaps, be desirable to supersede the use of the oil 

 by some other contrivance. 



7. INSTRUMENT FOR THE CONDENSATION OP WATER BY THE PRES- 



SURE EXERTED BY WATER AT GREAT DEPTHS OF THE OCEAN. 



(Invented by Professor Parrot ofDorpaL) 



This instrument consists of a hollow glass cylinder terminating below 

 in a hemisphere. The upper end is to be closed by a cover which 

 is screwed on. Through this cover a tube, open at the top, passes, 

 fixed in so tightly as to allow no air or water to pass. This tube, 

 when inserted into the glass cylinder, descends nearly to the bottom, 

 and, after a bend, reascends again nearly to the top, where it ter- 

 minates in a horizontal tapering piece with a small opening at the 

 end. The tube is filled with mercury up to the open point, and the 

 cylinder with water. By a small opening in the cover, which is 

 again closed when the screw of the cover is quite home, the small 

 quantity of superfluous water which may be in the cylinder passes 

 out while the cover is screwing on. It is clear that the pressure of 

 the water in the ocean is exerted on the water in the cylinder entirely 

 through the medium of the mercury in the tube, and that the con- 

 densation of the water is exactly measured by the quantity of mer- 

 cury forced out of the tube through the small opening at its end. 

 The tube is furnished with a scale, on which the proportion which 

 the volume of the mercury wanting in the tube bears to the volume 

 of water in the cylinder is read off f. 



8. COMPARISON OF THE PRUSSIAN WEIGHTS AND MEASURES WITH 



THE NEW ENGLISH WEIGHTS AND MEASURES. 



(By Professor Eytelwein.) 



One English inch, at 62 Fahr. = 0.971140 Prussian inch at 61J 

 Fahr. 



An English pound avoirdupois, of 7000 grains, = 31.018012 

 Prussian loth, 32 of which are a Prussian pound. 



An imperial gallon = 253.95383 Prussian cubic inches J. 



* Petersburgh Transactions for 1830. f Ibid. 



