312 Rev. Mr WhewelTs General Method 0/ calculating 



ing to calcedony. When they are steeped in an acid, they 

 part with the calcareous matter, and the macerated remnant 

 intimates by its appearance that the two substances occurred 

 in alternate layers ; the calcedony, however, prevailing towards 

 the surface. 



The specimens now exhibited will serve to give a correct 

 idea of the nature of this incrustation, and furnish evidence 

 of its recent origin, since it invests even the loose fragments of 

 the rock. We know the Neptunian origin of calcareous sta- 

 lactites ; and here they occur alternating with those in which 

 silica predominates. Need we hesitate, then, to conclude that 

 the calcareous and siliceous ingredients were suspended in the 

 same menstruum, and deposited under similar circumstances ? 

 We may conjecture that the water was aided by heat, by al- 

 kalies, or by carbonic acid or carburetted hydrogen, render- 

 ed powerful by compression ; but these are mere mental ef- 

 forts to avoid a conclusion which the circumstances of the 

 case justify, but which militates against our theoretical preju- 

 dices. 



Manse of Flisk, 22d February 1825. 



Art. XXV. — Notice of the Rev. W. Wheweli's General 

 Method of calculating the Angles made by any Planes of 

 Crystals, and the Laxos according to which they are formed,* 



Ihe object of Mr Wheweli's inquiry Avas to obtain a new 

 system of notation for expressing the planes of a crystal, and 

 their laws of decrement, and to reduce the mathematical part 

 of crystallography to a few simple formula; of universal appli- 

 cation. The author proposes to represent each plane of a 

 crystal by a symbol indicative of the laws from which it re- 

 sults, which, by varying only its indices, may be made to re- 



* This Notice is composed of an abstract of Mr Wheweli's paper, as 

 read before the Royal Society on the 25th November 182t, and published 

 in the Journal of Science, No. XXXVI. and of a short notice of the For- 

 mula? themselves, which Mr Whewtll was s-o good as to send us at our re- 

 quest. — En- 



