VOL. XXIX.] PHILOSOPHICAL TRANSACTIONS. 243 



exceedingly small compass, and by that pressure a little changed in shape; to. 

 which the muscles of the abdomen, distended so as to be scarcely discernible, 

 could give but little, if any assistance. 



The awe that people have here for dead bodies, though never so prejudicial 

 to the living, would not suffer her friends to let me make any further inquiry; 

 so that I can send no account of any other part. The same error hindered me 

 examining another woman, who died here about a week after, of an ascites 

 which she had had 40 years, any further than to be satisfied she had ^ gallons 

 of water contained between the duplicatures of the peritonaeum, and none in 

 the cavity of the abdomen. 



A new Method of determining the Parallax of the Sun, or his Distance from 

 the Earth \ by Dr. Halley, Sec. R.S. N° 348, p. 454. Translated from 

 the Latin. 



It is well known that this distance of the sun from the earth, is supposed 

 different by different astronomers. Ptolemy and his followers, as also Coper- 

 nicus and Tycho Brahe, have computed it at 1200 semi-diameters of the earth, 

 and Kepler at almost 3500; Riccioli doubles this last distance, and Hevelius 

 makes it only half as much. But at length it was found, on observing by the 

 telescope, Venus and Mercury on the sun's disk, divested of their borrowed 

 light, that the apparent diameters of the planets were much less than hitherto 

 they had been supposed to be; and in particular, that Venus's semi-diameter, 

 seen from the sun, only subtends the fourth part of a minute, or 15 seconds; 

 and that Mercury's semi-diameter, at his mean distance from the sun, is seen 

 under an angle of 10 seconds only, and Saturn's semi-diameter under the same 

 angle; and that the semi-diameter of Jupiter, the largest of all the planets, 

 subtends no more than the third part of a minute at the sun. Whence, by 

 analogy, some modern astronomers conclude that the earth's semi-diameter, 

 seen from the sun, subtends a mean angle, between the greater of Jupiter and 

 the less of Saturn and Mercury, and equal to that of Venus, viz. one of 15 

 seconds; and consequently, that the distance of the sun from the earth is 

 almost 14,000 semi- diameters of the latter. Another consideration has made 

 these authors enlarge this distance a little more: for since the moon's diameter 

 is rather more than a quarter of the earth's diameter, if the sun's parallax be 

 supposed 15 seconds, the body of the moon would be larger than that of Mer- 

 cury, viz. a secondary planet larger than a primary one, which seems repug- 

 nant to the regular proportion and symmetry of the mundane system. On the 

 contrary, it seems hardly consistent with the same proportion, that Venus, an 

 inferior planet, and without any satellite, should be larger than our earth, a j 



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