364 



CATALOGUE. — PRACTICAL ASTEONOMY, GEOGRAPHT. 



It was, however, found in the course 

 of the survey, that the degree perpendicu- 

 lar to the meridian in latitude 50°4l was 

 <ill83.3 fathoms, which is 88 fathoms 

 less than on Bouguer's hypothesis nor 

 did this measure agree witli any elliptic 

 spheroid. From the coraparison of this 

 degree with that of the meridian, the 



ellipticity appeared to be .008751, or -1— ph. tr. 1795. 



148 

 Laplace thinks that different meridians 



«re diffeiently curved, but that in Europe 



the ellipticity ofthe osculating spheroid is — — 



From the measurements in America 



«nd at the equator, the ellipticity appears 



lobe L_ 



493 

 From the greatest number of European 



mtasurements, 



From the new measurements in France 



compared with the equatorial degree ~ 



334 

 From the variation of the pendulum, 



taking .00567 as its limit, ' 



(32 



1 



178 



From the lunar motioni 



Laplace. 



I 



3'2g.4 



1 Nich. 



300 Vin. 12. 



From the new measurement in Lap- 

 land, compared with the Peruvian degree — ~ Melander- 

 ' * 313 hielm. 



A minimum of errors in Lapland, 

 France, and Pferu, gives 



Lambton's measurement, which was 

 not extremely accurate, gives 



The variation of gravity being ^Lj, 

 the ellipticity becomes _2_ Robison. 



319 

 Dalby makes the earth's equatorial radius 3 j 80932 

 fathoms, its semiaxis 3473056. Ph. tr. 1791. 



Subsequent measurements 3491420 and 3408007 , or 

 7935 and 7882 miles. Ph. tr. 1795. 



Density of the Earth. 



Bertrand sur hi structure interieure de la 

 terre. 8. Zurich, 1752. M. B. 



Maskelyne's proposal for measuring tlie at- 

 traction of a hill, read 1772. Ph. tr. 1775. 

 495. 



Maskelyne's observations made on SchehaU 

 lion. Ph.tr. 1775.501. 



The sum of the two deflections 11". 8 : on a rough com- 

 putation, the mean density of the earth appears to be at 

 least twice as great as that of the hill, which seems to be 

 an entire rock. 



Pringie on the attraction of mountains. 



4. London, 1775. Ph. tr. 1775. 

 Hutton's calculations for determining the 



mean density of the earth. Ph. tr. 1778. 



689. 



Finds the specific gravity | of that of Schehallion, an* 

 concludes that it is about *\. 



♦Cavendish on the density of the earth. 

 Ph. tr. 1798. 469. Nich. 11. 446. Gilb. 



ir. 1. 



A horizontal arm with two balls was suspended by a wire, 

 so as to vibrate 4 or 8 times in an hour : two leaden 

 weights, applied near to the balls, produced a deflection of 

 about 7 inches in the first case, and about 3 in the second t 

 from a mean of many such experiments, the earth's density 

 is found by calculation 5.48, without a chance of an error 

 of ^, confirming Newton's conjecture of 51. Magnets ia 

 the place of the weights produced no effect. 



Cavallo. N. Ph. K. 11. 



The deepest mine is not more than 2400 feet deep. 



According to the investigations detailed in Robison's El«- 

 ments, it may be calculated, that, supposing the decrease 

 of gravity yi;;, the ellipticity is such as would be assumed 

 by a coat of water surrounding a sphere of the density i.O 

 or as if i of the attractive force of the spheroid were collected 

 in its centre. 



Observations for finding the Situation of 

 Places. 



Grischow on latitudes and longitudes. N. C. 

 Petr. V. 417. 



Alcala sobre las observationes di latitud y 

 longitud en el mar. 4. Madr. 1796. 



R.y. 



