612 PHILOSOPHICAL TRANSACTIONS. - [anNO 16q3. 



goods in deep water. 21. The general philosophy of the motion and figures of 

 the air, the sea, and of seasons, of timber, iron, hemp, tar, brimstone, tallow, 

 &c. and of their several uses in naval affairs. 22. An account of five or six of 

 the best navies of Europe, with that of the arsenals, magazines, docks, yards, 

 &c. 23. An account of all the shipping able to cross the seas belonging to 

 each kingdom and state of Europe. 24. An account of all the chief commer- 

 cial parts of the world; with mention of what commodities are originally carried 

 from, and ultimately to, any of them. 25. An account of the chief sea-fights, 

 and all other naval expeditions and exploits, relating to war, trade, or discovery, 

 which has happened in this last century. 26. Of the most advantageous use 

 of telescopes for several purposes at sea. 27. Of the several depths of the sea, 

 and heights of the atmospheres. 28. The art of making sea-water fresh and 

 potable, and fit for all uses in food and physic at sea. 



Extract of a Letter from Sir Robert Redding, late F. R. S. concerning Pearl- 

 ashing in the North of Ireland ; communicated to the Editor by Dr. Lister, 

 R.S.S. N" 198, p. 659. 



I have sent you four or five of the shells,* and a few of the pearls found in 

 them, though clouded and little worth, taken out of the river near Omagh in 

 the county of Tyrone, in which county are four rivers abounding with these 

 muscles, all emptying themselves into Lough Toyle, on which the town of 

 Derry stands, and so into the sea. There are also other rivers in the county of 

 Donegal, and a river near Dundalk, also the Shure running by Waterford, 

 the lough called Lough Lean in Kerry, which afford the like fish ; and no doubt 

 there may be many more, that I do not know ; all these places are at the feet of 

 very great mountains. 



The manner of their fishing is not extraordinary; in the warm months, before 

 harvest is ripe, while the rivers are low and clear, the poor people go into the 

 water and take them up, some with their toes, some with wooden tongs, and 

 some by putting a sharpened stick into the opening of the shell ; and although 

 by common estimate, not above one shell in a hundred may have a pearl, and 

 of those pearls not above one in a hundred be tolerably clear, yet a vast number 

 of fair mercantile pearls, and too good for the apothecary, are offered to sale 

 by those people every summer assize. I saw one pearl there that weighed 36 

 carats, and was valued at 40l. and had it been as clear as some others produced 

 therewith would certainly have been very valuable. 



The young muscles have no pearls in them. The shell is fastened with two 



* The shell here described is the m^a margaritifera, Linn. 



