English plate brass, in form of a rod. English plate brass, in form of a trough. Steel rod. Cast-iron prism. Glass tube. Solid glass rod. expansi have be Leng .04948 0.07422 0.1237 3.38938 33.8931 67.7876 101.6814 0.15 in.05048 0.07572 0.1262 3.45788 34-5788 69.1576 103.7364 its thin Leng inch; v.05052 0.07578 0.1263 3.46062 34.6062 69.2124 103.8168 straight Leng 0.3 inc.03052 0.04578 0.0763 2.09062 20.9062 41.8124 62.7186 very sar An Account of the Trigonometrical Operation, whereby the Distance between the Meridians of the Royal Observatories of Greenwich and Paris has been determined. By Major-General William Roy, F. R. S. and A. S. Introduction. 18. THE trigonometrical operation which becomes the subject of this work, had its commencement, as will be remembered, in the measurement of a base on Hounslow Heath in 1784, an account of which was given to the Royal Society in the following year. In the spring of 1787, Sir Joseph Banks opened (through the official intercourse of his Majesty's secretary of state, the Marquis of Carmarthen, with the ambassador at the court of France) a correspondence with the Academy of Sciences, regarding the cooperation expected on their part, for connecting the triangles which we were now preparing to extend along the English coast, with those formerly executed on the coast of France, opposite to Dover. And Dr. Blagden had engaged to assist in the business, on the appointment of the Royal Society, whenever we should be enabled to assign any probable time, for the different parties to repair to their respective coasts, for the aforesaid co-operation. About the same time likewise, a paper was laid before the Royal Society, intended as a sketch of the mode proposed to be followed in carrying the scheme into execution; for which purpose it was accompanied with a general map, shewing nearly the disposition of the triangles. For several months of the spring and summer of 1787, Mr. Ramsden had been seriously at work, in endeavouring to finish the |