ORRERY. 
famous engine aa we defcribed, (fee Currinc-Engine, ) 
as the invention of the late Rehé, and alfo that the expenfe 
e ueftion is mov 
the f{uperior end o rtical a fufficiently to detach wheel 61 as before ftated : at the out- 
cock C, ch vertical arb>r, therefore, re alfo ina ward end of faid bar, L L, is fixed the dotted cock of 
folar day: end of this diurnal and vertical Jig 3, and alfo the unfeen cocks of the horizontal arbor for 
arbor is a pinion o , let down throug e made in the the weekly handle ; the bar 
plate CC, till the eae end of the arbor velba on alittle cock 
feen {crewed to the under fide of the faid plate: this plate, 
CC, carries the annual train underneath it, avd the reft of 
the wheelwork above it; the pinion of £5, above referred 
to, drives the wheel 120, to which is fixed a pin on of 23, 
feen the loweft, and driving the wheel 61, to which whee: is 
again made faft, above it, the pinion 14, to drive the larger 
or annual wheel 241 round ina folar year, which it does 
with great accuracy, the whole train —< x re 
88 S$ 23 14 
59904 L.?. 1 ¢¢ et * 3 £4 oh om 
161’? * E 365° 5" 48™ 40.1921 28. 
This train is reprefented as having the arbors in a ftraight 
line, in order that their conneCtion may be feen and under- 
ftood, but in reality they are placed round the centre of the 
box, and occupy 240° of a circle, as may be feen in the cal- 
er laid down in fg. 3. of Plate VIII., which we have 
inferted for the ufe of the inftrument-maker, who might 
to an arbor 
that turns between the dotted cock M, a nd the upper face of 
the plate, but projects through it to receive the wheel cee 
and its pinion 23 below, to which they are pinned o 
common tube ; and the period in which this arbor sevalven is 
eight — namely, ~ 5 : above the plate, and on this fame 
» below, and into a cock 
jeQing arbor F, which we have called 
carries the hour index, both which are feen in the perfpedtive 
drawing in Plate VIII. The wheel 61, already ple fae as 
one of the annual train, has its teeth eouneded with another 
pinion of 23, hid under the plate, but feen fideways in the 
detached fig. 3, which gives motion to a third pinion, of the 
ame number of teeth, placed on the vertical arbor, work- 
ing inthe dotted cock, which arbor, therefore, turns alfo 
in eight days, like the firft pinion of 23; ie ae ver- 
tical arbor 1s a bevel wheel of 32, feen cleariy in fg. 3, 
turning another of fimilar fhape on the fee cccl ae with 
28 teeth, which arbor, therefore, alfo turns in feven days, and 
anfwers to the index on the cover of the box, already called 
the week-hand. The ufe of this fecond horizontal arbor, or 
arbor of a week, which 1s reprefented as fhortened, and 
briana its cocks, is to receive the fame handle a heneyee a 
otion 18 required to be given to the planets, after 
oe "diurnal eye of the earth is ftayed, which is effeSed 
thus; the wheel of 61, under the plate CC, is not fup- 
ported by this plate immediately, but turns on a pin or ftud 
imferted into a long bar of brafs L L, feen endwife in Js: Ie 
Vou. XXV. 
L, has a hole tapped in its 
lower face, and a {crew with a milled head afcends through 
the bottom of the box, in which it has a little play, to allow 
for the motion of the bar, which bar it then fixes underneath 
the box, in either the attached or detached fityation of 
wheel 61. The utility of this contrivance will appear more 
clearly hereafter. ‘The third arbor that appears above the 
box is the annual arbor of wheel 241, which carries the 
third or yearly hand ; a pa calliper is fo contrived, that 
the three arbors for t s form an equilateral triangle 
round the centre of ie be, for the om of ar ed of 
appearance. In the centre of the plate, crewed. 
faft a rod of fteel, D D, perfe@ly perpendicular, apeard 
of nine inches long, and fomewhat more than r of 
an inch in diameter, into the top of “whi ich the fan's 5 ee is 
which thirteen concentric tubes are 
ithi 
eoasiiors dir mixe 
nature, confifting ay of fimple ratios, or pairs of aac 
4H 
