By the sale of his medicines and of his pamphlets relating to medicinal plants, some of which ran through many editions, he made large sums of money.
Before passing on to a consideration of Hill's botanical work brief comment may be made on his literary activities other than those already alluded to. It has already been mentioned that much of his output represented mere hack work, so that it is not surprising to learn, in view of the large amount of work he did, that a certain proportion of it was careless and slovenly, and shewed marked signs of undue haste in production, with the result that his reputation suffered. One work, entitled Letters from the Inspector to a Lady with the genuine Answers (1752), is an amorous correspondence not remarkable for its reticence of statement; it reminds one of a similar, but more proper, correspondence, which had a vogue a few years ago.
Hill did not always write for gain, thus Thoughts concerning God and Nature (1755) shews him in a different light. This was written from conscientious and religious motives in answer to a book written by Henry St John Viscount Bolingbroke, and was published at a loss, for the number printed, even if all were sold, would not have paid the expenses of production.
His dramatic pieces were of a mediocre nature, and with regard to his novels and other works Baker[72] states that "In some parts of his novels incidents are not disagreeably related, but most of them are nothing more than narratives of private intrigues, containing, throughout, the grossest calumnies, and aiming at the blackening and undermining the private characters of many respectable and amiable personages. In his essays, which are by much the best of his writings, there is, in general, a liveliness of imagination, and a prettiness in the manner of extending perhaps some very trivial thought; which, at the first coup-d'œil, is pleasing enough, and may, with many, be mistaken for it; but, on a nearer examination, the imagined sterling will be found to dwindle down into mere French plate."
In addition to his literary work Hill found time to undertake official duties. In 1760 he was gardener at Kensington Palace, a post which brought him in an income of £2000 per annum[73]; also he was Justice of the Peace for Westminster. According to Mrs Hill[74] he was nominated Superintendent of the Royal Gardens, Kew, and as such he is described on his portrait; his nomination, however, does not appear to have been confirmed, for Thiselton-Dyer[75] states that there is no evidence of his ever having occupied such a position. Hill also advised, at the request of the Earl of Bute, the governors of various islands regarding their cultivation, for which work he received no remuneration[76].
Anatomy.
Anatomical investigations during the eighteenth century were very barren of results, no real advance upon the discoveries of Grew, Malpighi and others being made. The work of Hill in this field forms no exception to this statement; and, although he accomplished a fair amount of anatomical work, his investigations apparently were without result in the advancement of this particular branch of knowledge.
In 1770 Hill published a small octavo volume on The Construction of Timber. In order that other investigators might benefit from his experience he fully described and figured the instruments used; of particular interest is a small hand microtome with which he cut his sections. This ingenious tool was the invention of Cummings, and does not differ in essentials markedly from some the writer has seen in use; Hill claims that when the cutter was particularly sharp sections no thicker than a 2000th part of an inch could be obtained. The microscope was made by Adams under the direction of Hill and his patron, unnamed in the book, but in all probability Lord Bute, and embodied some improvements on earlier instruments. This microscope is figured in Carpenter's work on The Microscope and its Revelations[77].
The Construction of Timber is well arranged: the work begins with a general description of the tissues and their disposition in a thickened stem; then follows a more detailed account of the separate tissues; and finally much space is devoted to a comparison of different tissues in various plants.
Hill's account is fully illustrated with copper plates; his figures of sections are not highly magnified, some not more than twelve times, and their quality is not equal to the best in Grew's Anatomy.