( 1 8 8 ) 
“ of Obfervations, to be collated with the Calculus, 
“ and the Errors noted in an abacus : From whence, 
“ at all Times, under the like Situation of the Sun 
“ and Moon , I might take out the Corre&ion to be 
“ allowed. 
“ And having by me the Sextant I made to 
“ obferve the Southern Stars at St. Helena , in 
“ the Year 1677, I fixed it for this Purpofej re- 
“ folving to have continued to obferve, till I had 
“ filled my Abacus , fo as it might have the Effed 
** of exa£t Lunar fables, capable to ferve at : Sea, 
“ for finding the Longitude with the defired Cer- 
tainty. 
i( With this Defign s I applied the Leifure I had 
“ procured myfeif about the Year 1683, to obferve di- 
“ ligently, as often as the Heavens would permit, the 
“ true Place of the Moon, efpecially as to Longitude \ 
“ and in the Space of about fixteen Months I had 
“ gotten near two hundred feveral Days Obfervations, 
“ molt of which I collated with the Horroxian 
“ Theory ( whofe Calculus is fomething more com- 
“ pendious than that of Mr. Street J and having pla- 
“ ced the Errors in an Abacus , I perceived how re- 
“ gular the Irregularities were, and that where the 
“ Moon had been exactly obferved formerly, at the 
Diftance of one or more Periods of two hundred 
“ twenty-three Months* I could even predict the 
“ Error of the fables, with a Certainty not much 
•“ inferior to that of the Obfervations themfeives. 
“ But this Defign of mine was foon interrupted by 
* £ unforefeen domeftick Occafions, which obliged me 
“ to poftpone all other Gonfiderations to that of the 
a De- 
