Memoirs for a natural history of animals. Containing the anatomical descriptions of several creatures dissected by the Royal Academy of Sciences at Paris / Englished by Alexander Pitfeild [!] ... To which is added an account of the measure of a degree of a great circle of the earth, published by the same Academy, and Englished by Richard Waller.

French Academy of Sciences

Date:: 1688

Credit: Memoirs for a natural history of animals. Containing the anatomical descriptions of several creatures dissected by the Royal Academy of Sciences at Paris / Englished by Alexander Pitfeild [!] ... To which is added an account of the measure of a degree of a great circle of the earth, published by the same Academy, and Englished by Richard Waller. Source: Wellcome Collection.

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$‘24 Rie a A Needle in the Year 1666 had no declination fenfible, and in the Year 1664 it declined 4o! towards the Za/f, the variation thereof having been every Year abowé2o% ast 91 n° AR: TY OLE IX OR concluding in fine.the Magnitude: of a Degree, and by F confequence that of !the, Earth, ät'remains. yet to know what parts of the Meridional\Diftances wei Chave:/meafured with the Toife of Paris, do anfwer to Minutes and Seconds, confidering them as parts of a-great Circle which fhould' be defcribed round about the Earth. Tis upon this occafion that we are obliged to fearch in the Hea- vens thé Meafire of: the Earth; for we muft: neceflarily have recourfe tothe difference of the Latitudes: of: the: two placés-eftabliflied undet one and thefame Meridian; and iby thisitneans come toi the know: ledg of the Atchiof the|Heavens comprifed betweenthe:Zeniths: of the faid Placespthe: witichaArchois alike to:that which we have meafured upon the Earth. But before we pafs to the Celeftial Obfervations, it will be to the purpofe to fhew: after] what: manner .the,Inftruments were verified with which the obfervations were made ; which is here fo much the more neceflary, forthat the Tellefcopes which we made ufe of might have had fome latent defect, which could not be known, but by a particular Proof. ; 62 Plate the The firft Figure of the 3drplatereprefents.the Quadrant fitted upon third. its Foot in the ordinary manner as for. taking; of heights, or for di- *~ Suppofing then that before the reinverfion, one has marked upon the Limb of the Quadrant, the point D, where the plumb line beats, and after the reinverfion one has alfo mark’d the point E, where the plumb line is to be hanged, the Point C taken in the middle of the Interval DE. fhall determine the beginning of the divifion of the Quadrant,and ifafterthe inftrument be put into its former pofition the plumb line comes to beat upon.the point C,the Tellefcope fight muft ne$

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