On the Eocpeditions io the North Pole. 279 



signing the degree of pressure equivalent to the stroke of a pile 

 engine, the effects were not found to agree with the laws of fall- 

 ing bodies. M. de Cessart endeavoured to compare the per- 

 cussive and pressive forces, by reducing equal cones of lead to the 

 same thickness by the blow of a ram, and by pressure. M. Ron- 

 delet tried to accomplish the same object by means of the dyna- 

 mometer of M. Regnier*; neither of these gentlemen found the 

 effects to be proportional to the heights of the falls f; conse- 

 quently we must either suppose this law to be incorrect, or that 

 the motion is partly destroyed by the re-action of the supports. 

 Now the experiments of Camus tend to prove the latter suppo- 

 sition to be correct; but the theorv given in the first part of this 

 letter does not suppose any part of the velocity to be destroyed 

 by being transmitted to the supports, which appears to be the 

 cause of the difference between it and the results of the experi- 

 ments, and therefore requires to be considered anew, as it is not, 

 in its present state, sufficiently correct for any practical purpose. 

 That a part of the velocity is destroyed by the supports is easy 

 to conceive, because, I believe it may be shown, that the ve- 

 locity of the motion transmitted through the length of the bar, 

 will be greater than that with which the point struck will de- 

 scend. I am, sir, yours, &c. 

 Grove End, April 11, 1818. Thomas TreDGOLD. 



XLVII. On the Expeditions to the North. Pole. By M. Malte 

 Br UN J. 



ooME English writers have already indulged themselves in illu- 

 sory conjectures on this enterprise ; they describe Greenland as 

 bursting from the icy barrier which surrounds it. They repeat the 

 traditionary reports of the last century, respecting some whale- 

 ships said to have reached the pole, and even to have passed on 

 the other side of it. They presume to doubt the existence of 

 land to the north of Baffin's bay, although Baffin was the best 

 informed and most judicious seaman England could boast of; 

 and they even flatter themselves, that commerce will be carried 

 on in a direct route from London to Canton, by the pole, which 

 makes a distance of only 2,600 nautical leagues, whilst that by 

 the Cape of Good Hope is 5,500 leagues. 



Two men, however, of great authority, do not participate in 

 these exaggerated anticipations. — Mr. Scoresby, an experienced 



* Rondelet's Art de Bdtir, tome iii. p. 22 — 32. 



"t" Tliesc experiments were certainly not all applicable to the care in 

 question ; that is, to establish the relation between the pressive and percus- 

 sive forces, as far ay ieg;irds drivijig piles. 



X From the Journal Uvi DiOaCx. 



S 4 Greenland 



