THE SUN’S DISTANCE FROM THE EARTH.

New Zealand Mail, Issue 311, 6 April 1878, Page 20

THE SUN’S DISTANCE FROM THE EARTH.

TO THE EDITOR OB' THE NEW ZEALAND MAIL,

Sir, —The distance of the Sun has been lately given by Sir G. Airey as 93,321,000 miles, with parallax 8 TOO. This has been deduced from the Delisle process only, and must be accepted with great caution. Eoucalt’s experiment on tlie velocity of light gives B'B6 ; observations on Mars, 1862, give 8'855. Leverricr, from a method of his own, gives B'B6. From all these, and other methods, Newcomb, the American astronomer, gives as the most probable value S’S-18 ; or distance, 92,393,000. All results from observations of Venus on the Sun are untrustwoithy, from tlrh difficulty of getting sharp measurements from the contrast between the intense brightness of the Sun and the dark planet. The photographic results have all turned out untrustworthy. We must wait patiently for the results of Mr. Gill’s work at Ascension Island on Irene and Mars last year. It is well worth remembering that this distance is thus obtained from the great pyramid thus: If a line drawn from the centre of the pyramid base to one of the angles be divided into ten parts, nine of these parts gives the height of the pyramid. If this height be multiplied by ten raised to the ninth power the result is closely upon 92,000,000 miles. Lord Lindsay, who spent £SOOO in preparing from the Venus transit, has destroyed his work as of no value, and intends to watch ll iora to gain the Sun’s parallax. He lent his valuable telescope to Mr. Gill, so that his expenditure will not be wasted. Any number of observations can be taken of Mars, or of these minor planets, and these must be more valuable than tho e which can be taken only at one time, and under great excitement, at a Venus transit. -—I am, Sic., Patience. Wellington, March 29.