20 ON LIFE BOATS. 



Alalite where The alalite has been discovered in a vein in the mountain 

 of Ciarmetta, situate beyond that of Testa-Ciarva, at the 

 Alp of la Mussa, near the village of Ala. It is commonly 

 accompanied with green or pale yellow primitive garnets, 

 and emarginated garnets of a hyacinth red, which have no- 

 thing in common with the topaz. It was these last that Mr. 

 Bonvoisin designated by the name of topazolites, because 

 he thought them of a pleasing colour, which he compared 

 with the yellow of the topaz. 



The pyrophy- J sna n ava ii m yself of this opportunity to announce, that 

 ' Mr. Haiiy has found the substance called pyrophysalite by 

 Messrs. Hisinger and Berzelius, an analysis of which was 

 given by these gentlemen in the Annales^de Chimie for May, 

 1806*, to be a variety of the aluminous fluate of silex 

 (topaz), of a greenish white colour, and nearly opake. 



IV. 



Letter from Sir Thomas Clarges, Bart, of Sutton upon 

 Derwent, toW. Annesley, Esq,, on the Subject of Life 

 boats. 



Dear Sir, Portsmouth, Nov. 29, 1808. 



Lukin's patent A Promised to give you an account of Life-boats. In the 



boat. fi rst pl aC e there is one by Lukin, late a coach-maker in 



Long- A ere, who has published a treatise on it. It is a row- 

 boat, and on the sides has something similar to mine, a hol- 

 low case made air-tight, running the whole length of the 



Buoyed up by boat. A bird must have wings on each side to support it in 



cork, and air- the air; and thus we technically give the name of wings to 

 ig eaaes. those parts on the sides of a boat, that tend to give it buoy- 

 ancy. On the outside of the airtight cases in Lukin's boat 

 is a layer or belt of cork : so that his wings are formed of 

 airtight cases, to buoy up the boat in the water like blad- 



Balanced by ders, and of cork. To prevent the boat from upsetting, it is 



an iron keel. furms h ed with a cast iron keel. 



Objections to The objections to Mr. Lukin's boat are these. The air- 

 tight cases are not in compartments, or chambers, like mine ; 

 and therefore, if forced through by a rock, or striking againft 



it 



* See our Journal, vol. XIX, p. 33. 



any 



