Page:Philosophical Transactions - Volume 095.djvu/280

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Dr. Herschel on the Direction of the

Table V.

Quantities and Sum of the least real Motions.

Sirius 0",65437
Arcturus 1,28784
Capella 0,10887
Lyra 0,11281
Aldebaran 0,01104
Procyon 0,04998
Sum 2",22491

The result of this investigation is, that by admitting a motion of the sun towards λ Herculis, the annual proper motions of our six stars, of which the sum is 5",3537, may be reduced to real motions of no more than 2",2249.

When first I proposed λ Herculis as an apex for the solar motion, it may be remembered that a reference to future observations was made for obtaining greater accuracy.[1] Such observations we have now before us, in the valuable Tables from which I have taken the proper motions of the six stars; and I shall prove that, with their assistance, we may fix on a solar motion that will be considerably more favourable.

We have already shown, that to ascertain the precise place of the best apex is attended with some difficulty; but from the inspection of the figure which represents the quantities of real motion required when λ Herculis is fixed upon, it will be seen that, by a regular method of approximation, we may turn the line SP into a situation where all the angles of the

  1. See Phil. Trans, for 1783, p, 273, line 8; and page 274, line 4.