t figures force upon us, and we
lose the opportunities of admiring both the astonishing amount of work
done and the beautiful way in which the material is handled by a master.
But I am tempted to give one very small illustration of the numerical
results from near the end of the paper. After discussing the Washington
results, and amply fulfilling the promise made in the preceding extract,
Mr. Chandler compares them with the Pulkowa results, and shows that the
Earth's Pole must be revolving from west to east, and not from east to
west. And then he writes down a simple formula representing this motion,
and compares his formula with the observations. He gives the results in
seconds of arc, but for the benefit of those not familiar with
astronomical measurements we may readily convert these into feet; and in
the following tables are shown the distances of the Earth's Pole _in feet_
from its average position,[6] as observed at Washington and at Pulkowa,
and the same distances calculated according to the formula which Mr.
Chandler was able to write down at this early stage. The signs + and - of
course indicate opposite directions of displacement:--

WASHINGTON.

_Deviation of Pole._

+-------------------------------------+
| Date. | Observed.| Formula. |
|-------------------------------------|
| 1864, Dec. 28 | -28 feet | -23 feet |
| 1865, Mar. 19 | - 1 " | -12 " |
| " June 1 | +15 " | +12 " |
| " Aug. 11 | +22 " | +23 " |
| " Oct. 9 | +11 " | +15 " |
| " Dec. 13 | -17 " | - 6 " |
+-------------------------------------+

PULKOWA.

_Deviation of Pole._

+-------------------------------------+
| Date. | Observed.| Formula. |
|-------------------------------------|
| 1865, July 25 | -18 feet | -12 feet |
| " Sept. 9 | + 3 " | + 3 " |
| " Nov. 22 | +26 " | +22 " |
| 1866, Feb. 22 | +18 " | +13 " |
| " June 4 | -11 " | -18 " |
| " July 17 | -16 " | -23 " |
+-------------------------------------+

Of course the figures are not exact in every case, but they are never many
feet wrong; and it may well be imagined that it is a difficult thing to
deduce, even from the most refined observations, the position of the
earth's pole to within a foot. The difficulty is exactly the same as that
of measuring the length of an object 300 miles away to within an inch!

Mr.