[104]. In the earlier part of this interval of time, and before he became more seriously engaged in those great works and researches, the construction of his Orrery, and the Observation of the Transit of Venus with the operations preparatory to it, which about that time engrossed his attention, he occasionally amused himself with matters rather speculative than practical: though he very seldom devoted any considerable portion of his time to things which he did not consider as being in some degree useful.
The following is one of those instances in which his active mind was diverted from severer studies, to some objects of a more playful nature.
In the year 1767, some ingenious country-gentleman published in Messrs. Hall and Sellers’s paper, under the signature of T.T. the result of calculations he had made on Archimedes’s famous vaunting assertion, Δος που στω, και την γην κινησω. Mr. Rittenhouse published, some short time after, calculations (or rather the result of calculations) of his own, on the same problem. This appeared in a piece under the signature of “A Mechanic,” dated the 8th of October, 1767: and a reply to it, by T. T. dated October the 29th, appeared in the same paper. These little speculations will be found in the Appendix. It is not improbable that Mr. Rittenhouse, under the disguise of “A Mechanic,” appeared in print on this occasion, for the purpose of drawing the attention of ingenious men to subjects of this nature.
[105]. It was between the years 1766 and 1770—the interval of time above mentioned,—that the two important circumstances occurred, which gave great celebrity to the reputation of Mr. Rittenhouse, as an astronomer: these were the Construction of the Orrery invented by him, and the admirable result of his observations of the Transit of Venus, as published in the Philosophical Society’s Transactions.
Amidst those objects of importance in which he was principally occupied, he occasionally amused himself with matters of minor consequence. Among other things, he contrived and made, in the beginning of the year 1767, an ingeniously contrived thermometer, constructed on the principle of the expansion and contraction of metals, by heat and cold, respectively. This instrument had, under glass, a face upon which was a graduated semi-circle: the degrees of heat and cold corresponded with those of Fahrenheit’s thermometer; and these were also correspondently designated, by an index, moving on the centre of the arch. Its square (or rather parallelogramical) form, its flatness and thinness, and its small size—together with its not being liable to the least sensible injury or irregularity, from any position in which it might be placed,—rendered it safely portable; insomuch, that it could be conveniently carried in the pocket.
He presented one of these metaline Thermometers to Dr. Peters, in June 1767: Another, which he made for himself, was a considerable time in the hands of Mr. Barton, at Lancaster. They were found to agree very well with Fahrenheit’s. In a letter to Mr. Barton, dated the 26th of July 1769, he said—“You will oblige me by sending the metaline thermometer by..., and let me know the greatest height you have seen it, this season, Fahrenheit’s thermometer, in my Observatory, not exposed to the sunshine but very open to the air, was 94½° on the 5th of this month, at 3 in the afternoon; which is the highest I have ever seen it.”
[106]. The Rev. Ebenezer Kinnersley, A. M. Professor of English[English] and Oratory in the college of Philadelphia. This venerable and worthy man, who was a clergyman of the Baptist church, was a very eminent Electrician. In this branch of philosophy, he was an able lecturer and ingenious experimentalist: and perhaps to no person—at least in America,—were his cotemporaries more indebted, than to him, for the light which he shed, at a very early day, on this interesting and pleasing science.
[107]. According to the American historian, Marshall, Lord Berkeley assigned his interest in the Jersies to Penn and his three associates, in the year 1674; and they, soon perceiving the inconvenience of a joint property, divided the province, in 1676, with Carteret, who still retained his interest: to him they released East-Jersey; and received from him, in return, a conveyance for the western part of the province. The Duke of York resigned the government of East Jersey to the proprietor, retaining that of West-Jersey as an appendage to New-York, until August 1680; when, on a reference to Sir William Jones, the title was decided against the Duke: after which, he formally released all claim upon East-Jersey. Soon after this, Carteret transferred his rights to Penn, and eleven other persons of the same religious persuasion, who immediately conveyed one half of their interest to James Drummond, Earl of Perth, and eleven others; and these, in March 1683, obtained a conveyance from the Duke of York directly to themselves.—During these transactions, continual efforts were made to re-annex the Jerseys to the province of New-York. [See Marshall’s Introduction to the Life of Washington, ch. vi.]
[108]. There will not be another transit of Venus over the Sun’s disk, until the 8th of December, 1874; which, it is probable few persons now living will have an opportunity of observing, astronomically: And from that time, down to the 14th of June, A. D. 2984, inclusively,—a period of upwards of eleven centuries,—the same planet will pass over the Sun only eighteen times. There will be one other such transit of this planet, within the present century; after which there will not be another, during the term of one hundred and twenty-one years and an half. [See Table of the Transits of Venus over the Sun, in Lalande’s Astronomie; vol. ii.]
[109]. There had been but one of these transits of Venus over the Sun, during the course of about one hundred and thirty years preceding the transit of 1769; and, for upwards of seven centuries, antecedently to the commencement of that period, the same planet had passed over the Sun’s disk no more than thirteen times. [See Lalande’s Table, before referred to.]