It appears, that when Mr. Rittenhouse sent the foregoing description of his projected Orrery to Mr. Barton—that is to say, on the 27th of March, 1767[142]—the “foundation” of it was “laid.” But, notwithstanding his earnest wishes prompted him to the utmost diligence, in his exertions to finish it, many circumstances concurred to retard its completion. The magnitude of the undertaking—the multiplicity of the work—and, perhaps, the difficulty of sometimes readily procuring, even from Philadelphia, the necessary materials,—all conspired, to prevent as early a completion of the machinery as he had anticipated: and, added to these causes of unavoidable delay, was the yet unabandoned pursuit of his professional business. ----- Footnote 142: It appears that Mr. Barton must have transmitted to the honourable Mr. T. Penn, in London, a description of the Orrery, very soon after it was publicly communicated to the Philosophical Society in Philadelphia; for, a letter from Mr. Penn to that gentleman, dated July 22, 1768, contains this remark—“The account you give me of Mr. Rittenhouse’s Orrery, is what I could not have imagined could be executed in Pennsylvania; and I shall be much pleased to see a copper-plate of it, for which I would make that gentleman a present, for his encouragement; or, perhaps he may be induced to bring it hither, and exhibit it, by publicly lecturing on it.” Had Mr. Rittenhouse taken an Orrery to England, and it appears by his letters of March 15, 1771, and Feb. 3, 1772, quoted in the text, that he had seriously intended going thither, he would, very probably, have derived great emolument, as well as fame, by delivering lectures on astronomy, adapted to his orrery; and it is probable, that, in addition to the public encouragement he might reasonably have calculated upon, Mr. Penn would have patronised him, with his usual liberality. Of the disposition of that worthy gentleman to befriend him, Mr. Rittenhouse seems to have been fully sensible: for, in a letter of the 11th of December, 1768, to Mr. Barton, he said—“I am very desirous to send Mr. Penn something: as the orrery is not finished, perhaps a description of it, with draughts of the clock I have just made, may answer the purpose, together with some little instrument: I shall be glad to have your thoughts on the matter.” It may be proper here to remark, that no engraving, or drawing, could give an adequate idea of the orrery: and that the clock, mentioned by Mr. Rittenhouse, was one of those of which a short notice is introduced, immediately after the original description of the orrery, in the text. -----