XXX. Account of the construction of the new national standard of length, and of its principal copies

Abstract

In presenting this Report to the Royal Society, I must solicit their indulgence for many imperfections, arising from the circumstances under which the task of writing it has devolved on me. Through the whole account, I have to record the proceedings of others, and (in a great measure) I have to describe the trains of thought in the minds of others, which have determined those proceedings. The first part of the investigations for restoration of the Standard was made by Mr. F. Baily; but the largest proportion by very far was effected by my much-valued friend the Rev. R. Sheepshanks. These have successively been removed by death from their labours on the Standards. On the eve of the day on which Mr. Sheepshanks was struck down with mortal disease, he was engaged in micrometrical comparisons of Copies of the Standards; on the day following the deadly stroke, the Royal Assent was given to the Bill for legalizing the Official Standards which he had constructed. Under circumstances like these, it is evident that the documents relating to the final operations must have been left in great confusion. In the earlier portions (the papers relating to which had been, in a measure, roughly brought into order), the difficulty is mainly of another kind. Although from official relation and private friendship I was in constant and unreserved intercourse both with Mr. Baily and with Mr. Sheepshanks, and though I was cognizant of every step taken, and sometimes examined the apparatus used, yet I never actually made an observation. It is possible therefore that my want of familiarity with the operation may sometimes make my statements imperfect. I trust, however, that in the main my account will be substantially correct. It will be necessary for me briefly to revise the history of the British Standards for some time anterior to the work which forms the essential subject of this paper.