Note 135 — MEMOIRS OF THE LIFE OF DAVID RITTENHOUSE; ANTERIOR TO HIS SETTLEMENT IN PHILADELPHIA.

Besides the Orrery here referred to, as the invention of the celebrated mechanic and watchmaker, Mr. George Graham, a like machine was afterwards contrived by Mr. James Ferguson, an eminent Scotch mechanic and astronomer, and another planetarium of the same kind, by Mr. William Jones, an ingenious mathematical instrument maker, of London. From the planetarium or orrery of Graham, however, as a model, all the modern orreries, prior to Mr. Rittenhouse’s, appear to have been taken. The one constructed by Mr. Rowley is said to be very similar to that invented by Dr. Stephen Hales.

But the idea of a planetarium, somewhat similar to the Rittenhouse-orrery, seems to have been conceived by Huygens, who died in 1695. A collection of this celebrated philosopher’s works was printed at Leyden in the year 1724 and 1728: and in these will be found the description of a planetarium; “a machine” (says Lalande, in speaking of the one contemplated by Huygens,) “which represents, by wheel-work, the revolutions of the planets around the sun and of the moon around the earth, in their durations and natural dimensions; with their excentricities, their inequalities, and their inclinations towards the ecliptic.” See Lalande’sLalande’s Astron.