45 6 
A 
s 
T R O 
had equal altitudes at Greenwich. 
Was the 
: watch too 
faft or too (low f 
i6h. 
4 '- 
15"’ 
I I 
IO 
9 
2) 4 
54 
6 
Half elapfed time 
2 
27 
3 
Time of firft altitude 
I I 
IO 
9 
Star’s tranfit by the watch 
13 
37 
I 2 
Star’s R. A. -J- 24b. =2 
28 
23 
50 
Sun’s R. A. 
14 
46 
15 
Difference 
13 
37 
35 
Sun’s R. A. November 6, 
14 
46 
15 
November 7, 
!4 
5° 
15 
Increafe in 24 hours 
0 
4 
O 
As 24V1. 4'. : 24I1. :: 13^37'. 35". 
: 13 
35 
19 true time 
Time per watch 
!3 
37 
I 2 
Watch too faft 
0 
I 
53 
To draw a Meridian Line by equal Altitudes of the Sun, or 
a Star. If equal altitudes of the Sun be taken, as before 
diredled, and the place of the index on the horizon-circle 
be carefully noted at eacli time of obfervation, the mid¬ 
dle degree or part between each, will be the place where 
the index will (land, when the fights of the quadrant are 
directed to the fouth, or north, according as the Sun is to 
the Jouthward or northward of the place of obfervation 
at noon. Set the index to this middle point, and diredt 
the fights of the quadrant to fome remote and fixed ob¬ 
ject on tlie Earth. This objedt will be a fouth meridian 
mark, and will ferve to fet the quadrant at any future 
time. Then take up the inftmment, and, after letting the 
index to o, place it again on the table, or fupport, and 
move the whole inflrument, not by any of its parts, but 
entirely about upon the table, till the lights are truly di- 
redted to the meridian mark. Adjlift the horizontal cir¬ 
cle, and the index will then lerve to lhevv the true bear¬ 
ing of any object; becaufe the diameter joining the two 
zero’s, or oo’s, anfwers to the meridian line. 
If the table, or fupport, be immoveable, it will be pro¬ 
per to make three marks, or indentations, to receive the 
points of the fcrews ; by which means the horizontal cir¬ 
cle may be irwftantly, at any time, fet in its proper polition, 
with refpect to the cardinal points of the horizon. It of¬ 
ten happens, that there is not any window in a houfe from 
which the Sun can be feen morning and evening. In this 
cafe, the meridian may be determined by obferving equal 
altitudes of the pole-liar, or any other near the pole. 
To find the Time by the Sun’s Tranfit over the Meridian. Ad- 
juft the quadrant to the cardinal points, a (hort time before 
noon. Set the index to o, and elevate the quadrant, fo 
that the lhadow of the fight with the crofs-wire may fall 
upon the other. As the inftant of apparent noon ad- 
proaches, the bright fpot formed by the Sun’s light thro’ 
the lower hole in the former fight will be feen approach¬ 
ing the mark on the latter. If the obferver chufes to look 
at the Sun, he rauft now put up the dark glafs, and apply 
to the obfervations. The inftants when the firft limb or 
edge of the Sun appears to touch the perpendicular wire, 
and the latter limb appears to leave it, muft be noted by 
the clock or watch. The middle time is the apparent 
noon. Or, if he chufes to obferve by the bright (pot on¬ 
ly, the inftant when the fpot is feen upon the mark is the 
apparent noon; and this, correfted by the equation of 
time, will (hew how much the clock is to-o faft or (low. 
To find the Time by an Obfervation of the Sun's Altitude and 
Azimuth. Adjuft the inftrument to the cardinal points, 
and obferve the Sun’s altitude. Take notice likewile of 
the angle of azimuth from the meridian, as (hewn by the 
index. Then, As the fine complement of the Sun’s de¬ 
clination : the fine complement of the altitude :: the fine 
of the azimuth : the fine of the Sun’s library angle. 
N O M Y. 
Which laft being reduced into time, by allowing 15° to one 
hour, and in proportion for the other parts, gives the ap¬ 
parent time, if after noon ; but, if before noon, it muft be 
deduced from twelve hours, to give apparent time, which 
muft be corrected by the equation of time. 
Ex. Stippofe that, on tire 21ft of June, the Sun’s alti¬ 
tude was obferved to be 46° 25', and 112 0 59', the decli- 
nation being 23 0 29'. 
As the cofine of the Sun’s declination 23 0 29' 9-9624527 
Is to the cofine of the altitude 46° 25' 9 8384769 
So is the fine of the azimuth 112° 59', or its 
compl. 67 0 i 1 9-9640797 
I 9 : 8oz 55 6 6 
9-96245 27 
To the fine of the horary angle 43 0 47' i3 f/ 9-8401039 
As 15 0 : ih. :: 43 0 47' 13" : 2I1. 55' 8", the apparent or 
true time paft noon, or to 9I1. 4'. 52". before noon; but 
neither of thefe times will agree with a watch which mea- 
fures time equally. 
The equation of time for noon at Greenwich is T 15-9", 
the daily difference 13"; therefore, As 24I1. : 13" :: 2I1. 
55'. 8". : 1.5"; confequently 1-5" added to 1' 15-9^', or 
1' 17-4", is the equation of time to be added to the given 
hour: but 2I1. 55'. 8". added to 1' 17", gives 2b. 56'. 25". 
the time paft noon by the watch. 
It may be necelfary to remark, that, whenever you ap¬ 
ply the equation of time to that immediately deduced from 
calculation, you muft add or fubtradt as the Nautical E- 
phemeris directs; and, if the time is not very near noon, 
you muft make a proportion as above ; but, if you apply 
the equation of time to the time by the watch, you muft 
fubtraiTt where the ephemeris direfts you to add, and vice 
verfa. 
We cannot conclude this Treatife, without adverting to 
the difficulties which many perfons make, in reconciling 
certain palfages of Scripture with the known and eftablifh- 
ed phenomena of modern aftronomy. After w-hat has 
been dated of the difcoveries of Dr. Herfchel, very little 
doubt remains of the fixed ftars being funs, which from 
analogy may be naturally fuppofed to have planets revolv¬ 
ing round them, in the lame manner as the planets re¬ 
volve round our Sun, formed for the abodes of rational 
inhabitants ; notwithllanding Mofes only ftates, in the firft 
chapter of Genelis, that they were created '■'■forfigns, and 
for feafons, for days, and for years-," from whence many 
have abfurdly concluded, that they were formed folelv for 
the purpofe of being attendants upon our Earth. But can 
it for a moment be imagined, that the great Author of 
Nature, who acts with fuch infinite wifdom in all his ope¬ 
rations, would have created fo many glorious funs, adapt¬ 
ed to the molt important purpofes, merely to give a glim¬ 
mering light to the inhabitants of this Earth, when we 
fhould have been more benefited by one additional Moon. 
Belides, a very fmall part only of the (tars can be feen by 
the naked eye; fo that inftead of the bulk of mankind 
being benefited by the whole, by far the greater part can 
only be difcerned by means of the telefcope, a modern in¬ 
vention, which but few people, comparatively fpeaking, 
can have an opportunity of tiling. It is obvious, there¬ 
fore, that, when Mofes made life of the above language, 
lie confined hinifelf to thofe things only that concern the 
Earth, and alluded to the vifible appearance of thole ftars 
which fhould thenceforward become the admiration of the 
new-formed creature man, and be made lifeful to him, not 
only by affording fome additional light to the Earth, but 
alfo by enabling him to diftinguilh times and feafons, 
nights and days; and by ferving the many and valuable 
purpofes of navigation; which, though not then under- 
ftood, muft undoubtedly have been in the omtiifcient view 
of the Creator. And in this fenfe all the univerfe may 
perhaps be fakl to be reciprocally ufeful as figns and fea- 
i’ons, &c. to each other. 
From 
