after Passing into Harbours. 379 



the depth is uniform and the quay walls are vertical, the 

 following formula may be tried for cases in which D is not 

 less than 50 feet : — - 



H = height in feet of waves in the open sea. 

 x = reduced height of waves in feet at place of observation in 



the interior of the harbour. 

 b = breadth of entrance to harbour in feet. 

 B = breadth of harbour at place of observation in feet. 

 D = distance from mouth of harbour to place of observation 

 in feet. 



I B 50 B \ ; J 



This formula I have found to give good approximations at 

 several harbours where the heights of the waves were regis- 

 tered. When H is assumed as unity, x will represent the 

 reductive power of the harbour. — I am, yours faithfully, 



Thomas Stevenson. 



Professor Jameson. 



SCIENTIFIC INTELLIGENCE. 



GEOLOGY AND GEOGRAPHY. 



1. Extent of Glaciers in the Polar Regions. — On every side of 

 the southern pole, on every meridian of the great South Sea, the 

 seaman meets icebergs. Not so in the north. In the 360° of longi- 

 tude, which intersects the parallel of 70° north (about which paral- 

 lel the coasts of America, Europe, and Asia, will be found to lie), 

 icebergs are only found over an extent of some 50° of longitude, and 

 this is immediately in and about Greenland and Baffin's Bay. In 

 fact, for 1375 miles of longitude we have icebergs, and then for 7635 

 geographical miles none are met with. This interesting fact is, in 

 my opinion, most cheering, and points strongly to the possibility that 

 no extensive land exists about our northern pole, — a supposition which 

 is borne out by the fact, that the vast ice-fields off Spitzbergen shew 

 no symptoms of ever having been in contact with sand or gravel. Of 

 course, the more firmly we can bring ourselves to believe in the ex- 

 istence of an ocean-road leading to Behring's Straits, the better heart 



