404 n The Longitude. 



Mr. Dolling, and Mr. Down, of Bridport. They immediately 

 communicated their cafes of vaccine inoculation, without ap~ 

 fearing to he acquainted with Dr. Jcnner's works. 



Have you reafon to think that Dr. Jenncr, previous to the 

 publication of his firft work on vaccine inoculation, was at 

 all acquainted with the facls contained in the correfpondcn.ee 

 delivered in? 



A. I have laid, I apprehend the parties all performed their 

 inoculations independent of each other. — Withdrew. 



THE LONGITUDE. 



The following letter from a gentleman in Greenock relates 

 to a matter of fo much moment, that our readers will regret 

 the death of the perfon who contrived and executed the in- 

 firument alluded to. It is fortunate however that the appa- 

 ratus is flill in exiftence, as further experiments, and a more 

 minute examination of its ftxu6ture, may perhaps lead to a 

 difcovery of its principles. 



All that can be inferred at prefent is, that poffibly a well 

 pcrffed magnetic ball, though it may remain flationary (ex- 

 cepting the change occaiioned by "the magnetic variation), 

 while kept in the fame place, may poffefs a property which, 

 on carrying it eaftward or weftward from that fpot, may oc- 

 caiion a revolution on its axis proportioned to the diftance. 

 Should any thing like this turn out to be the fa£t, we may 

 yet fee that accompli (lied which has hitherto baffled every 

 human effort. 



But be that as it may, ingenious men will endeavour to 

 profit by the hint which the following letter prefents : 



"Greenock, Aug. 2. 

 " An affair of fo much confequence to mankind as the 

 following it were criminal in me to concealj I therefore re- 



?iueft of you to make it as public as poffible among your fea- 

 aring and philofophical friends. 



" Our mutual friend, before his departure laft fall for 

 Philadelphia, conftru&ed a machine, apparently fimple, but 

 which is infinitely more valuable to navigation than the 

 compafs. It was brought to me, together with his log- 

 book, by a fellow paffenger homewards, who unluckily had 

 paid no attention to the ufe of the apparatus ; which was 

 the more unfortunate, as our friend died within three leagues 

 of land. 



" It is a magnetic ball, floatingin a bafon of quickfilver. 

 The ball is painted all over, to keep the quickfilver from pe- 

 netrating the pores, which might embarrafs the evolutions, 

 5 which 



