A letter from Paris concerning some new electrical experiments made there / [John Turberville Needham].

  • Needham, John Turberville, 1713-1781.
Date:
1746
Catalogue details

Licence: Public Domain Mark

Credit: A letter from Paris concerning some new electrical experiments made there / [John Turberville Needham]. Source: Wellcome Collection.

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    Extract of a Letter from Paris, concerning 3 o fome New Electrical Experiments made lately there. $ ' * f ■: ’ Af\ ft S I R, Paris, July 4, N. S. 1746 AS I have been my felf, fince my coming hither, greatly entertained with the curious eleCtrical experiments I have feen at monfieur le Mourner's, I hope fuch an account as I am able to give of them, will not prove dilagreeable to you, notwithftanding you may very fhortly expeCt a better from that gentleman himfelf, who intends writing to you by the firfl opportunity. Had I been verfed in drawing* fo that I could have delineated the apparatus I have feen, I might both have fhortened my defcription, and have rendered my felf more intelligible. As it is, you mull excufe long periods, take the will for the deed, and let the fingularity of the faCts themfelves make amends for the manner of relating them: till monfieur le Monnier's own letter fhall come, like the fun after the dawn, and give you full fatisfa&ion. The electrifying glafs ufed by monfieur le Monnier is an oblong fpheroid, whole diameter from pole to pole is four or five inches longer than that at the equator, which is about twelve inches. Each of thefe poles is ter¬ minated in a item, or portion of a hollow cylinder, about three inches in length, and one in diameter, fpirally embofied on the outfide into a large male fcrew : to each of thefe male fcrews is adapted a female fcrew of wood, clofed at one extremity, with a piece of fteel excavated in the centre, to receive the fteel pivots upon which the electrifying glafs turns. Thefe female fcrews of wood are fo formed at their open extremity, that they grafp and cover as much at the poles, as nearly renders what appears of the glafs fpheroid a perfeCt fphere 5 this with, a defign, that the wood may fix the more effectually, and embrace the electrifying glafs. From the exterior furface of one of thefe wooden female fcrews a circular ledge rifes, and projects to the height of about two inches ; thz ambitus of which ledge is excavated, to receive the cord that turns the electrifying glafs. This is what they ufe here inftead of our tubes, and with furprifing effeCts, fuch as greatly furpafs what you have yet feen in England. The electrifying fpheroid is turned by means of a wheel near five feet in dia¬ meter, with the fame motion, and exaCtly in the fame manner, as the fpindle is turned round by the fpinning-wheel; allowing a due proportion to the frame, upon which the glafs fpheroid is mounted, that it may anfwer to the wheel that turns it. The Tides of this frame, which ftand perpendicular to the horizon, are near as ftrong and as large every way, as the pods of an or¬ dinary clofet door; and, with the ledges that join them at top and bottom, form A * a rectangular,