306 PHILOSOPHICAL TBANSACTIONS. [aNNO 1753. 



taking them for absolutely exact, have concluded Sir Isaac Newton's reasonings 

 on that subject to be faulty ; while Father Boscowich, a Jesuit at Rome, making 

 them quite loose and uncertain, thinks no argument at all can be drawn from 

 them, concerning the earth's figure : far less in confirmation of the Newtonian 

 theory. In opposition to these two extremes, equally contrary to reason, as they 

 are to each other, Frisi writes the treatise now before us; in the introduction to 

 which he shows, 1 . That, though the ratio of the axis of the earth to its equa- 

 torial diameter is, from M. de Maupertuis' operations in Lapland, and afterwards 

 in France, that of 177 to 178; and by the theory only 229 to 230; yet the 

 difference is no more, than what might arise from a mistake of about 60 toises 

 in the measure of either of the two degrees, that are compared, or of 30 toises 

 in each of them. Or, suppose the measure of the arcs to be exact, the same 

 difference might be owing to an error of 4 or 5 seconds in the astronomical part. 

 And such errors, or others equivalent to them, in a course of so many combined 

 operations, our author considers as difficult to be avoided. But he adds, if the 

 observations of M. de Maupertuis, and his fellow academicians, seem to differ 

 from the theory, those of Messrs. Bouguer and de la Condamine exactly agree 

 with it; according to whom, a degree at the equator, containing 56753 toises, 

 and in latitude 49° 22' 57183 toises, the difference of the axis and equatorial 

 diameter comes out to be -j-J-g • 



In answer to Boscowich, and those who make no account of the observations, 

 our author allows, that if they were such as Cassini, and some other academicians, 

 made in France, of the measure of a parallel of latitude, they could not be much 

 depended on; that method being liable to several obvious inconveniencies. But 

 he insists that, with the excellent instruments which were used, and considering 

 the distinguished skill of the observers, as well at the polar circle as in France, 

 and at the equator, the error on one degree of the meridian could not exceed 

 60 or 70 toises, which is a degree of exactness not only sufficient for the deter- 

 mination of the first question, viz. whether the spheroid of the earth is fiat or 

 long; but likewise to found an agreement between the observations and the 

 theory, as near as can be expected or desired. 



The work itself is divided into 10 chapters: 



(1) De observationibus circa telluris figuram hactenus institutis. (2) De prin- 

 cipiis et hypothesibus quibusdam. (3) De rotatione corporum, et vi centrifuga. 

 (4) De mutationibus ex motu circulari ortis. (5) De attractione corporum ro- 

 tundorum. (6) De comparatione gravitatis in variis homogeneae sphaeroidis locis. 

 (7) De figura terrae. (8) De gradibus meridian] et parallelorum. (9) De loxo- 

 dromiis nautarum, de parallaxi lunae, et aliis ex eadem theoria pendentibus. 

 (10) De theoriag et observationum consensu. 



In chap. 1, we have a short history of the inquiries that have been made into 



