66 : New Patents lately Enrolled. - 
Fourthly, a gauge to determine the angle 
which the yarns in the outfide fhell make 
with a line parallel to the-centre of the 
frand when regiltering ; and, according 
to the angle made by the yarns.in this 
fhell, the length of all the- yarns. in the 
ftrand will be determined. 
Fifthly, by hardening up the frand, and 
thereby increafing the angle in the out. fide 
fhell, which compenfates for the ftretching 
of the yarns and the compreifion of the 
ftrand. ae 
The patent which Mr. H. took out in 
Auguft relates to the invention of a ma- 
chine that maybe worked by men or any 
ether power, and by means of which the 
regiftering may be commodiouily and. ef- 
feStually carried on. 
‘Without plates it will be impoffible for 
us to defcribe the peculiar contrivance. 
‘Thofe of our readers who are interefted 
will in courfe confult the fpecification it- 
_ felt at the: proper office. 

MR. RAND’S TELESCOPE. 
Mr. Cater Rand for his improved Mili- 
_tary and Naval Telefcope to.afcertain Di- 
tances and the Size or Extenfion ef Ob- 
je@s at Sight, by means of a new Micro- 
metrical adjuftment. 
This telefcope is made refraGting, achro- 
matic or refieCting, and the micrometer has 
four parallel hairs or wires fitted to filver, 
brafs, copper, or other well contrived con- 
verging and diverging plates, two of which 
parallel hairs or wires have a permanent 
and fixed value, and theother two are va- 
lued in proportion to their degree of di- — 
vergency, meafured in parts of a great 
circle, and are put into motion, governed 
and regulated by a proper mechanical 
movement which at one and the fame time 
acts upon the diverging or converging pa- 
raliel hairs or wires, and gives a vertical 
motion to a fcale by the fide ofa ftationary 
verniers or nenius index, whofe refpective 
divifions are calculated to meafure the mi- 
nutes of a degree of a great circle; the ver- 
nier or nonius at the fame time performing 
its proper office, fubdivides the minutes 
of the moving fcale into tenths, equal in 
value to 6" or feconds of a great circle read 
_ off from the bottom towards the top of the 
ards 
index {cale, placed to the right ef the mi- 
crometer {cale, immediately oppefite td 
if 
which is placed a {mall lens of fufficient 
a. 
fFebs sy. 
magnifying power for reading of the divie 
fions, and eafily direéted to its proper fo- 
cus to fuit the eyé of the obferver. 
The whole of the above apparatus (ex-- 
cept the lens which is fixed before the index 
at the diffance of, half an inch or there- 
abouts according te its focal diftance) is 
framed together and properly fitted on the- 
eye tube of the telefeope, which being 
brought to its proper focus in the ufual 
way for viewing objects, is then fitted for 
obfervation for mealuring the angle fub- 
tended by any object for finding its diftance 
by a fingle obfervation, if its height or 
fize be known, or by two obferyations and 
the intermediate diftance, when neither: 
-diftance, fize, nor height are’ knewn but 
both required, in’ manner following. Ifthe 
angle fubtended by any object be fought in 
the table of diftances placed on the cuthde 
tube of every telefcope, and its correfpond- 
ing tabular number be multiplied by the 
crown fize or height of the objeét in an 
meafure, the diftance of the objeét will be 
found in the fame meafure, It the height 
be required from the known diftance- the 
tabular number .correfponding te the angle 
as before divided by the diftance, will give 
the height or fize, and this by one cbfer- 
vation. Ifthe diftance and fize or height of 
-ancbject, or both, be’required when neither 
1s known, the intermediate diflance paced 
or meafured between two: ftations, multi- 
_plied into the larger angle fubtended by the 
object, and that product divided by the 
difference of the angles taken at each fta- 
tion or place of obfervation, will give the 
* diffance from the furthef Gation or place of 
obfervation; from which if the interme. 
diate diftance be taken, it will leave the di- 
ftance from the neareft place of obfervation 
to the object. Dividing the tabular num- 
ber as before by either diftance corre- 
{ponding with the fubtending angle, will 
give the fize or height of the obje@&.— 
Hence, at one fiation or place of obferva- 
tion, the diffance ef an object may be 
found if the angle fubtended by that eb- 
- ject be truly taken, and the fize or height 
be known, and the height or fize ifthe di- 
fiance be known. WHejice alfo, from two 
itatrons, or from two places of obferva-. 
tion, and the known intermediate diftance, 
both the diftance and heightor fize of an 
object may be found when neither of them. 
is known. , 
MONTHLY 
