110 : Newellian Sphere. 
-——this varies a few minutes from the requisite number. The 
aggregate amount for a given number of years can easily be 
compensated for, and the machine set forward er backward, 
to its proper station. 3654 divisions-are likewise made on 
the ecliptic circle, the { being appended to the 28th of Feb- 
ruary. These divisions aeeerens correspond to the first 
year after a bissextile. A deduction of 4, 4, or 2, of a day, 
rust therefore be made from the time pointed out by those 
divisions, on the 2d, 3d, or 4th year subsequent to a bissex- 
tile. 
The equation of time, or the sun fast or slow elock, is lik ke- 
wise shown on the ecliptic circle foreach ten days through the 
circuit of the year. The relative motions of the superior 
planets are such, that taking the ratio of any two that are ad- 
Jjacent, and comparing it with that as produced by the ma- 
chine, they will be found to agree to four places of came 
being as near an approach to coincidence as could be attain- 
without increasing vastly the size and number of ent in 
the wheels and the complexness of the machine. This small 
amount of deficiency or increase being = can easily be 
compensated for, for any given time sa egree of 
accuracy is ee throughout the other parte Neither 
bands nor cords are used in the communication of motion to 
any of the parts, so aie no irreg’ by 
and slipping which is geoorel an eeee 
ble consequence: of that mode of gearing. Motion is 
mitted in every case, save that of the faceaaae wheels a 
mentioned, by the intervention of toothed wheels and pinions. 
hen a train of these are combined, a certain degree of play 
in each is unavoidable, for the purpose of an easy motion, so 
that a slight degree of irregularity is perceived in the extreme 
parts. This irregularity will consequently produce a cor- 
responding disagreement in the mean motion of the heaven- 
ly bodies which the machine is intended to represent. ‘These 
deviations, however, being comparatively trifling, will not, itis 
believed, detract any thing from the merit of the machine as 
an assistant in instruction, in showing the general motions of 
the bodies in the ria Boa system, and in illustrating t 
ous phenomena which those bodies at certain times exhibit. 
For nice and accurate calculations, reference must be had; as 
in all similar cases, to figures. This is more peculiarly ne- 
cessary in determining the motions of the heavenly bodies, 
which, from their mutual and constant attractions, are ever 
