AS A MANURE. 243 



flrata, lying indeed on the furface; but if any operation of 

 nature fliould cover this with a deep load of other matter, it 

 would be comprefied and rendered very folid : and remaining 

 for ages in that fituation, might ripen into a fubftance very 

 like pit coal. See the Medical and Chirurgical Review for 

 November 1803. 



&. Mr. Anjiey's Tefwnony of the Ufe of Peat Duft and Peat Afhes. 



Sir, 



Houghton Regis, Dec. 3, 1801. 



I received yours, dated the 18th of November laft, in Teftimony of 

 which you requefted me to inform you what experiment I had Mr * Anfte y* 

 made from the turf duft, taken from Tingrith Moor. I have 

 made ufe of the afhes and duft near thirty years, and I fre- 

 quently lay on from eighty to a hundred bufhels per acre. 

 Our land is dry and very thin ftapled, owing to the chalk rock 

 laying fo very near the furface ; it encourages vegetation in 

 moift warm weather; but when hot and dry, the reverfe. 

 We never mix any other manure with it. It cofts about 

 four-pence per bufhel, including all expences. 



We chiefly fpread it on our feed grafs, clover, &c. 



I am, Sir, your humble Servant, 



JOS. ANSTEY. 



IV. 



On Spectacles. In a Letter from Mr. EzekiEl Walker, 

 To" Mr. NICHOLSON. 



Dear Sir, 



Lynn, February 16, 1805. 



IN a former paper, I pointed out a property in fpe6tac!es,Pofition refpedt- 

 which had been overlooked by the writers on optics; but as 1 " 6 f P c " acles » 

 feme of your readers entertain opinions contrary to mine, 

 the fubject feems to require further invefligation. 



What I have advanced concerning fpeflacles is, that we viz. that we fee 

 fee better by oblique, than by dired pencils of rays *. ^S^Sx*' 



Phil ofophical Journal, Vol. VII. p. 291. 

 K2 



rays. 



