r44 New Patents.—The Selenographia.....Steps for Carriages. 
pafling through the poles, interfeéts the 
equator at a right angle, in that point 
which is the mean centre of the. moon’s 
libration. The third reprefents the boun- 
dary of vifion, when the moon is feen in 
che mean ftate of libration, and where 
this boundary interfects the prime meri- 
dian at a right angle, the two polar 
points of the moon are firuated, of courfe 
each is at go degrees of diftance from the 
equatar. 
A particular defcription of the inftru- 
ment defigned to move this globe of the 
moon, with all the ufes to which it is to 
be applied, would be too long to be de- 
tailed in a publication of this nature 
(and without the copper- plates it could not 
be clearly underftood) ; but the follow- 
ang will give an idea of both. Upon the 
ftand, an hemifphere of brafs is placed 
within, and upon which the gicbe, and 
all the parts, are fixed, which give it 
motion. The bar which immediately 
communicates to the lunar globe all the 
motion from the other parts, enters it op - 
pofite to that point where the equator 
and prime meridian unite. Upon rs 
front are femicircles, which being vra- 
duated,. determine the quantity of mo- 
tion: given behind. When the globe is 
moved herizentally, it fhows the lbra- 
tion in longitude ; when moved bythe 
pinion vertically, it exhibits the libration 
in latitude. Upon the edge of the bra- 
zen hemi{phere are two marks, to denote 
the pole of the ecliptic, by an imaginary 
line drawn through them; round which, 
by means of a wheel, the apparent mo- 
tion of the moon’s pclar axis revolves, 
both points of it being kept at the dif- 
tance of two degrées and a half, by 
means of-a pin in that wheel, attach.d to 
its guide, and placed ous of its centre 5 by 
which a very peculiar motion is commu- 
nicated to the lunar globe. On the 
wheel are the figns of the zodiac, to fhow 
the points of fpace to which the moon’s 
polar axis is at all times direéted; and a 
moveable circle, on which are éngraved 
divifions re{peéting the periodical revo- 
lution of the moon, fhowing when the 
moon’s revolution, with refpeét to the 
ecliptic, as feen from the edrth’s centre, 
1s accomplifhed,, On the fame circle are 
likewife engraved the divifions of the 
moon's fynodical revolution, by a conti- 
nulation of the divifions, marking the days 
and hours, &¢. in a {pital dire€tion un- 
der rhe former, to fill up the interval 
which ts wanting between the accom- 
plithment of the periodical and fynodical 
revolution ; one index pointing to botlt. 
[ Feb: 
In the front, a graduated meridian is 
fixed within the hemifphere ; to this are 
attached the femicircles before men- 
tioned: one reprefenting the ecliptic’; 
and at right angles to it, another, named 
the Terminator; which, moving upon 
hinges, reprefents the boundary of light, 
in all ftates of the moon’s elongation from 
the fun. This terminator is defigned to- 
to fhow what fpots will appear in the 
plane of its illaminated hemifphere at 
any age of the moon, and in every de- 
gree of libration in latitude, longitude, 
and apparent polar obliquity. In front 
of the lunar globe, and tixed to the bot- 
tom of the brats hemifphere, is an arch, 
which fupports a fmail terreftrial globe, . 
to render familiar the effects of the 
earth's parallax, or diurnal and menftrual 
libration. For the convenience of obfer- 
vation, the terrefirial globe 1s made larger 
than the proportional angle which our” 
globe fubtends as teen from the moon ; 
but converging lines, upon u plane of 
brafs, reduce it to its proper Size, viz. 
about two-of the lunar degrees, at that 
end where this plate nearly unites ta 
the large giobe of the moon. 
This is a fight defeviption of the Se=- 
lenographia. Many curious-and fftruc- 
tive experiments may be made with it, 
tending to examine the principles of the 
rotation and libration of the moon. from 
the appearances which the furface of the 
moon exhibits, and which are reprefented 
by this apparatus. Befides which, it is ap- 
prehended that it will be very ufefui to 
thofe who are juft entering upon. the 
confideration of this fubjeét, being the 
means of communicating te fuch perfons 
general knowledge, as well as particular 
and curious circumftances, im a more 
ready and agrecable manner than by the 
ufual diagrams. 
Mr. THoMASON’sS STEPS FOR 
CARRIAGES. 
To November, 1796, Letters Patent 
were granted to Mr. EpwarpD THO- 
MASON, button-maker, of Birmingham, 
for his invention of in§proved ficps ‘vo 
coaches, chariots, landaus, ac. &c. 
The. fteps on this conftruétion, poffefs 
the peculiar convenience, that they may 
be let down and drawn up with the 
greateft eafe and certainty, by the perfon 
within the carriage, and do not require 
the affiftance of afervant. The conftruc- 
tion is fimple, and the motion is pra-. 
duced by means of fprings; to explain 
the application of which, would require 
the aid of drawings. | 
The 
