POLE STAR.

MEAN TIME OF TRANSIT (AT WASHINGTON) AND POLAR DISTANCE OF POLARIS,

From June 16 to August 1 both the upper and lower transits take place during daylight. The azimuth at the time of greatest Eastern or Western elongation can be easily computed from the formula:

sin A=

sin B cos l

where A denotes the azimuth, p the polar distance, and the latitude of the place.

DATE OF GREATEST ELONGATION.

To find the time of greatest Eastern or Western elongation, let H denote the hour angle, and I and p as before, then we shall have

And the hour angle in mean time is

cos IT=tan p tan l. HmH

0.0664846.

This quantity, Han, added to or subtracted from the time of transit given above, according to the elongation required, will give the mean time of the greatest elongation at any place whose north latitude is

a Andromed(Alpher'z) + 28 361 18.0 410 40.0 aLeonis (Regulus).
Pegasi (Algenib).
+14 42 1 13,2 10 44. 8 a Virginis (Spica).

Cassiopeie (schedir)....+56 3 0 42.2 +11 15. 8 a Bootis (Arcturus)..

a Arietis.

BPersei (Algol)...

aTauri (Aldebaran)...

a Aurige (Capella).. aOrionis (Betelguese). aCanis Majoris (Sirius). aGeminorum (Castor)

+233 +0 40.0 +12 38. 03Ursa Minoris. +40 37+ 1 39.9 +13 37.9 aCoronæ Borealis. +16 203 8.2 +15 6.2 aScorpii (Autares). + 45 54 + 3 47.6 +1 45.1 aLyræ (Vega). +7 234 27.6 +16 25. 6 a Aquila (Altair). 16 365 18.4 +17 16.4 aCygni (Deneb). +32 56 5.7 +18 3. 7aCephei BGeminorum (Pollux).. +28 146 16.6 +18 14.6 a Aquarii aCanis Minor (Procyou) +5 27 +6 11.6 +18 9.6 a Piscis Australis... aPegasi (Markab).

On Meridian Upper. Lower,

н, м.

H. M. +12 248-40.1 +20 38, 1 -10 4211 56, 5+23 54, 5 +19 38 +12 47.5 +0 45,5 +74 31 +13 27.5+1 25, 5

+27 1+13 49.71 47.7

-26 1414 59.32 57.3 +38 4217 9.3. 573 +8 38 +18 21.46 19 4 +44 58 +19 13.57 11.5 +62 13 +19 51.57 49.5 -0 45 +20 35, 8+ 8 33. 8

305+21 27.1 + 9 25.1 +14 44 +21 34.7 +9 32.7

To find the time of the star's transit add or subtract, according to the sign, the numbers in the second column of figures to the date of the transit of the pole star given above. Thus, for a Andromeda February 1. Lower Transit of Pole Star is 4 h. 45 m. 48. A M. to which add 10 h. 40 m, and we have 3 h. 25 m. 4s. P. M.; for December 1, we find 7 h. 81 m. 22 s. P. M., etc. APPROXIMATE PARALLAX AND DISTANCE IN LIGHT-YEARS OF SOME OF THE PRINCIPAL FIXED STARS. By light-years is to be understood the number of years light requires to travel from the star to us.

The determination of stellar parallax is one of the most difficult and refined problems in practical or observational astronomy. It is to find the angle which the semi-diameter of the earth's orbit subtends at the star-an angle always very small, as seen from the above table, and which cannot be measured directly, but by various processes too complicated to be explained here.

Two heavenly bodies are in conjunction" (d) when they have the same Right Ascension, or are on the same meridian, i. e.. when one is due north or south of the other; if the bodies are near each other as seen from the earth. they will rise and set at the same time; they are in "'opposition'' (8) when in opposite quarters of the heavens, or when one rises just as the other is setting. Quadrature () is half way between conjunction and opposition. By greatest elongation is meant the greatest apparent angular distance from the sun; the planet is then generally most favorably situated for observation. Mercury can only be seen with the naked eye at this time. When a planet is in its ascending'' (2) or "descending" (U) node it is crossing the plane of the earth's orbit. The term "Perihelion" means nearest, and "Aphelion furthest, from the sun. An occultation" of a planet or star is an eclipse of it by some other body, usually the moon.

ASTRONOMICAL PHENOMENA FOR THE YEAR 1915.-Continued.

I.-ECLIPSES.

In the year 1915 there will be only two eclipses and both of the sun, as follows: 1. An annular eclipse of the sun February 13-14 invisible in America. lies in the Indian and Pacific Oceans and the northwestern portion of Australia.

The path of the annulus

2. An annular eclipse of the sun August 10 invisible in America. The path of the annulus lies wholly in the Pacific Ocean. It is visible as a partial eclipse in the Sandwich Islands. At Honolulu the eclipse begins at 10h, 36, 8m. A. M., ends at 1h. 53 4m. P. M., Local Mean Time.

10 634 A. M. Ó
11 11 O P. M.

12 10 57 P. M. 68
14 3 20 P. M.

14 7 P. M.
14 10 7P.M.
A. M.

1811 21 7 21 1

23 8

24 10

26 12

Mar. 1 2

11

A. M.

P. M.

P.M.

A. M.
A. M.

A. M.

824 P. M.

A. M.

13 836 A. M.
14 124 A. M.
14 12 5 P. M. 6
17 4
19 1 A. M.
2010 A. M.
23 5 30 A. M.
P. M.

23 8 29 8

Apr. 3 9

P. M.

P. M.

A. M.

P. M.

511 10 10 11 7 A. M. 12 456 A. M. 12 840 P. M. 15 11 A. M. 19 4 15 P. M. 29 8 A. M.

May 1.1

21

in perihelion.

ŏ N. 7'. Y S. 54'.

N. 33'.

gr. elong. E. 18°.
gr. elong. W. 470.

stationary.
N. 24.

49 A. M. 9 715 A. M. 10 6 P. M. 11 12 43 A. M. 12 1

P. M. 9
A. M. 8

h S. 10 8.

superior.

22 8 15 P. M. O

gr. elong. E. 260.

17 7

HI, 9 N. 10 10'.
gr. elong. W. 28°.
S. 12'.

28 12

A. M.

in perihelion.

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17 12 P. M.

19 916 P. M.
22 9

A. M.

aaaa

ааааа ааааа да аа
AAOAC A2 Of Fif

12 8 P. M. D
13 935 AM. ?
15 7 P. M.
22 234 P. M.

26 2 P. M.

inferior,

stationary.
stationary.

gr. elong. W. 190,

stationary.

in aphelion.

superior