GUNTER’S SCALE. 
: The uf ufe of this inftrument is to find the hour of the 
day, the fun’s azimuth, &c. and other common problems 
of i globes as alfo to take the altitude of an object in 
“Bee is defeription and ufe more at large under the article 
Gunter's Quap AN 
-GUNTER’S Scales alte called By navigators abfolutely, The 
Gunter, i is a large plain feale, with variou s lines upon it, o 
we in working ie in age, Ke. See 
ALE me SaAiLl 
This init ent derives fi name from its inventor, Mr. 
Edmund Gunter, who vy rofeffor of aftronomy in Gre- 
tham college, and _firft publithed the feales of phe 
numbers, fines, and tangents, 1n his defcription of the c 
laff, in 1624. The errors which had crept into Gunter 8 
feale, by length of time and t negligence in the Bip alae a 
it, have been’ corrected by the late ge John Robertfon 
ian to the Royal Society, and the inilrument has bet 
re-conftructed, under his infpe€tion p32 with his improve- 
ments, by Meffrs. Nairne and Blunt, mathematical inftru- 
ment makers in London. See a defcription of this inftru- 
Ment in its erent ftate by W. Mountain, F. R. 8. pub- 
lifhed in 1778 
On one fi of the Ste reprefented Plate 1. Trigonom, 
=. ‘. od val lines of number numbers ; the line 
marked puies the line of artificial tangents, 
marked a ic line of artificial verfed fines, gabe 
Fr. 5. the artificial fines of the rhumbs, marked S. the 
tangents of the rhumbs, markedT. R. tw: line 
ia Mereator’ s chart, marked Aferid. and equal parts marked 
4. which, on the fhorter f{cales of a foot long, are ufually 
Pet ta oF ae gee hours, and inclinations of meridians. 
Qn the backfide of the fcale are the lines ufually found on a 
The lines of artificial fines, tangents, and number 
fo fitted on this ‘feale, by means of a pair o} of | com- 
that 
aoe: et thier’. in right-lined or fpherical 
il parts Se mat sri where se 
other; hence called na Gunters 
ae ules whos compaifes : : but he shat  andesiaods cog 
to ufe them with, may, by what. we have faid of Everard’s 
and Cog OF ’s fliding rules, ufe them without. See Srip- 
i ‘h Gunter’s {eale, as it has been lately improved, is 
made ¢ beer he two inches broad, and about half an 
fase: e face contains the natural feales; half the 
filled with feales of Ra ag parts; agit 
10, 19 15, 20, 25, 30, Cr 453 nd the tet: 
td py divifion fe Sie: is fo, and into 10 equal 
Parts, and alfo into. ual : on the other half of 
ual parts 
this face are “ont oe a toe lines which conftitute the plain 
i fuch fcales of rhumbs, chords, fine lox 
eae 4g 4 ye seen fitted to a sadhis’ df of tw 
nclies > the dialling fcales, viz. inclination of meri- 
the feve 
bers 
able, mae on a ee - piece of about 304 inches long, 
# an inch broad, and of the eee of the fcale. The 
other of thefe feales, or rig: 
ne * deaths: marked ee 
Fixed 2. A line of tangent rhumbs, marked: 'T. R. 
3. A line of verfed fines, marked ae. 
4. A line of fines, marked a 
5. A line of fines, marked Sin. 
stitiog { 6. A line of numbers, marked Num, 
7. A line of tangents, marked Tan. 
( 8. A line of tangents, mar Tan 
9. A line of number Num 
| ic. A line of meridian degrees to 50, 
Fixed < marked er. 
11. A line of meridian Segre from 50 
to about 74, m 
. line of degrees of longitude marked lida, 
Along this face an index or thin piec brafs, about an 
inch broad, is contrived to flide, which, going acrofs the 
edge of the {cales at right angles to it, we fhew on the 
feveral lines the divifions whick 
by han 
and in order to 
the perpendicular pe which a a tabbing will ae 
the flider in the box, and then by the motion of the 
zontal ferew, the greateit degree of accuracy poflible ai 
be obtained. Compaffes may be ufed with this fcale, as 
well as with the common Gunter, by firft bringing the 
radius on the flider exactly in a line with the others on the 
right hand and fixing it there. In a convenient part of this 
initrument are marked 10 fea-feet, each of which contains 
14. 8258 Englith inches, and each foot is divided into 12 
i. eaoll parts, called fea-inches. "The method of forming and 
graduating the feveral lineson Gunter’s s feale is as follows : 
the conftruétion of the line of numbers has been already 
for the line of logarithmic fines, it is to be 
ees, jut 
rs; ai 
from thence towards ord 
fons anfwering to thefe, feek in a eee of logarithmic fines 
the numbers exprefling the arithmetical complements of 
ral degrees, without the pans : take thefe num- 
from the feales of aa, parts by which the lines of 
hum mbers was formed, an 
from 90’. 
_ garithmic fines (or the 
apply them to the {cale of lines 
Then the ‘ithe setical complements of the lo- 
ge 
