VOL. LIIl.] PHILOSOPHICAL TRANSACTIONS. 677 



/. Of the Suns Distance from the Earth deduced from Mr, Short's Observations 

 relating to the Horizontal Parallax of the Sun. By Peter Daval, Esq., 

 V. P. of R. S. to James Barrow, V. P. of R. S. p. 1. To/. LJII. 



According to Mr. Short, the mean horizontal parallax of the sun is S".05. 

 Now this parallax is the angle which the semidiameter of the earth subtends, as 

 seen from the sun. Therefore as 8''.65 is to 36o^ (the whole periphery of a 

 circle) so is the semidiameter of the earth to the periphery of the orbit of the 

 earth round the sun. But 8". 65 is very nearly the 149826th part of 36o°, as 

 may be easily proved by division. According to the latest observations, the mean 

 semidiameter of the earth is 3958 English miles, which being multiplied by 

 149,826, produces 593,011,308 miles for the circumference of the orbit of the 

 earth. The distance of the earth from the sun is the semidiameter of this orbit: 

 and the periphery of the circle is to its semidiameter very nearly as 6,283,185 

 to 1. Therefore if we divide 593,01 1 ,308 by 6,283,185, the quotient, which is 

 very nearly 94,380,685, will give the mean distance of the earth from the sun in 

 English miles. 



As the orbit of the earth is an ellipsis, not a circle, the distance of the earth 

 from the sun will be greater in its aphelion, and less in its perihelion than here 

 assign ed- 



//. Observation of a Comet, which appeared in May 1759, made at the Hague. 

 By Peter Gabry, I.F.D., F.R.S. p. 3. 



Mr. Gabry observed the place of the comet on several days, as below. 

 May 2d 9'', its longitude Xffl ig° 12' 24'^, latitude 28° 40' 5'^ s. 

 3 9i. . 17 11 40 27 20 20 



6 g-L ..12 51 7 22 37 24 



7 9-L. . 11 59 14.... 21 1 44 



in. Observation of a Fiery Meteor, made at the Hague, Dec. 21, 1758. By M. 

 Peter Gabry, F.R.S. From the Latin, p. 5. 



About 8 in the evening of that day a remarkable light, or shining meteor, 

 appeared in the western part of the heavens, though the sky was then hazy and 

 calm. The air was temperate, the thermometer indicating 47°. Sometimes the 

 western sky seemed to burn, and the air with the lower clouds as if changed into 

 flames and smoke. At the same time also there shot up bright flames almost to 

 the zenith. 



A little after, the shining appeared very white, like a continued mass of fire ; 

 at first thin and weak; then increasing, it would extend from the north to beyond 

 the west, not unlike the light appearing in the horizon, just before sun-rise. 



