{*] 
number of authors have written on this fubjedl, than 
I was aware of; fo that, in all probability, we have not 
made any new diicoveries. I enclofe to you the re- 
fult of our enquiry ; and the few obvious reflexions 
which occurred. If they appear to contain any 
thing worthy notice, you will pleafe to communicate 
them to the Royal Society. 1 am. 
Dear Sir, 
Charter-Houfc, 
Jan. ioth, 1764, 
Your mod; obedient and 
Obliged humble Servant, 
John Hadley. 
The 
