As for the Invention of the Micrometer, which Mr. 
, A uz>out claims as his and Monfieur Picards, I fliall fay 
little to it, Mr. TortneUj having fufficiently prov’d it to 
be Mr. Gafeoignes, in the Philof. Jranfa^' No. And 
the OeCcriptions and Draughts of that, and Come other 
Jndruments of that kind, are now by me, in Mr. Gaf- 
ceigne's own Hand, to confirm Mr. Torvnekjs Account, 
if occafion were. 
(And, as Mr. Gafcoigne.'^2LS x\\Q, .firft that meafured the 
Diameters of the Planets, ^c, by a Micrometer r fb I 
fhall prove that he was the firft that applied Telefcopick 
Sights fo Aftronomical Inftruments. In a long Letter 
to his fagacious Friend Mr Crahtrie, of Jan. 164V 
C wherein he deferibes his Micrometer, and ihews his 
way of finding the Refradtions, the Moon’s Parallax, 
and how he meafured the Diameters of the Planets) 
Mn Gafeoigne tells him how the meafuring Glajfes, which 
he had been (peaking of, might be applied to a 
Quadrant. If, faith he, here (that is in the Diftindi- 
Bafe) place the Scale that meafures — , cr if here an 
Hair he fet, that it appear per f elf If through the 6 lafs—r., 
you may ufe it in a ^adrant\ for the finding of the Alti* 
fude of the leaf Star vifihle hf the Perfpeliive wherein it 
is. If the Night be (0 dark, that the Hair or the Point- 
ers . of the Scale he not to he feen, I place a Candle in n 
Lam horn, fo as it cafi Light fuficient into the Glafs^^ 
which I find very helpful when the Moon appear eth not, or 
it is not othenvije light enough. 
In another Letter, dated on Chriftmas Eve 1641. 
fwlierein he deferibes the Wheel Work of his Micro- 
meter, and Ihews how he could apply it to the taking 
of three Points ; and fpecifies his ()bfervations of the 
Diameters of the Sun and Moon; and mentions a Theory 
he had contriv'd of the Sun ; &c. and faith what pains 
he had taken in the Anatomy of the Eye) he tells Mr. 
Crab- 
