Stupendous Cavern^ 71 



as tlie cooling advances it becomes brown, and the redness of 

 this brown gradually increases till tlie ruby recovers its primi- 

 tive brilliant red colour. A green ruby suflered no change 

 fi'om heat. A blueish green sapphire became much paler at 

 a high heat, but resumed its original colour by cooling. — Ediyi. 

 Phil. Journal. • 



DIOCHRISM OF TOURMALINE. 



A specimen ol' diochritic tourmaline in the cabinet of Mr. 

 Allan exhibits the following singular contrast of colours. The 

 plate is cut perpendicular to the axis of double refraction, and 

 also to the axis of the prism. In the direction of the axis the 

 colour is a deep brilliant blue, and in the direction at riglit 

 angles to the axis the colour is a very pale red, approaching 

 to pink. — Edin. Phil. Journal. 



DAMP IX WALLS. 



An easy and efficacious way of preventing the effects of 

 damp walls upon paper in rooms, has lately been used (and 

 as we understand) with complete success. It consists of lining 

 the wall or the damp part of it with sheet lead, purposely 

 rolled very thin : this is fostened up with small copper nails, 

 which not being subject to rust are very durable, and the whole 

 may be immediately covered with paper. 



The lead is not thicker than that which is used in the chests 

 in which tea is imported, and is made in sheets of which the 

 width is about that of common paper-hangings. "We have 

 seen some which was rolled at the lead-mill of Messrs. Hutchin- 

 son and Co. at Pateley Bridge, in Yorkshire, and which was 

 as light as eight ounces and even four ounces to a square foot, 

 and yet quite impermeable to water. 



The remedy for a very disagreeable occurrence is thus ren- 

 dered not only easy but very cheap. 



STLPKNDOIS CAVERN. 



There was discovered about three weeks since, on the north 

 bank of the Black River, upon the land of James Le Hay, 

 es(j. opposite to the village of Watertown, an extraordinaiy 

 cavern, or grotto, the mouth of which is about ten rods from 

 the river, north of the Falls and of Cowan's Island. 



The great extent of the cavern, and the great lunnber of 

 spacious rooms, halls, and chambers, into which it is divided, 

 and the inunense quantities of calcareous concretions which it 

 contains, and different slates of those concretions, from the 

 consistence of lime mortar to that of the most bciuitiful stalac- 

 tites as hard as marble, rondtr it difficult, if not imjiossible, 

 to describe it; and I shall only attempt to give a faint desci ii)- 

 tion of three or f()ur rooms, 'I'he 



