The mean of the two nights gives for personal equation-

Riché observes earlier than Hall 0.121.

This result compares well with the result 0.116 for personal equation as derived from the difference of longitude with interchange of observers.

On the night of September 22 observations were made for the difference of longitude between Sault Ste. Marie and the Naval Observatory at Washington, D. C. Signals were successfully exchanged, but the observations were so broken by clouds that the work was not reduced.

AZIMUTH.

Observations for the azimuth of the line Observatory Sault Ste. Marie to station Azimuth were made by Mr. E. E. Heskell, U. S. assistant engineer, on four nights, March 2, 8, 14, and 19, by comparing the direction of the line with the direction of the star Polaris near western elongation. A few pointings on 51 Cephei near western elongation also were made on the night of March 19. The pointings to station Azimuth were made to a lamp accurately centered over the geodetic point. The length of the line Observatory to station Azimuth is 5 miles.

In determining the azimuth the large theodolite, Troughton & Simms No. 1, with a 14-inch horizontal circle, was used, reading with three microscopes. Pointings were made to the star direct and to the image reflected from mercury. The mean of the two readings is free of any error due to the axis of the pivots not being in a horizontal plane. The striding level was read during the observations, but no use was made of the readings in the reductions. The altitude of the light at station Azimuth was about 38' above the horizon. A correction for level was made to the readings on the mark deduced from the difference in the readings on the star direct and reflected. This was always small, never amounting to more than 0".3.

The method of observation was as follows: First the telescope of the theodolite was directed to the light on the distant station, bisecting it with the vertical wire, and the horizontal circle read; the telescope was then directed to the image of the star reflected from the mercury, and the time of bisection noted by the clock, and the horizontal circle read again; the telescope was then directed to the star, the time noted again, and the horizontal circle read. The observations were then repeated in the reverse order on the star, the image, and the light. In the next set the star was sighted on first, then the image reflected from mercury, and then the light; the observations were then repeated in the reverse order on the light, image, and the star. The telescope was then reversed by turning the telescope in a vertical plane around its pivot axis, the object glass passing through the nadir while the telescope was slightly lifted from the wyes to permit of the motion, and then the telescope revolved 180° in a horizontal plane and the observations repeated as described above. The observations thus made are for one position of the hori zontal circle. After these observations the circle was shifted by revolving the whole instrument by means of the revolving trivet on which it was mounted. Observations were made in two positions of the circle every night.

Clock No. 256, Bond & Son, was used in noting the time of observation of the star and its reflection from mercury.

The clock correction was determined by Würdemann transit No. 1 from the observation of 4 time stars and 2 slow stars, usually before the observations for azimuth were begun. The transit was mounted on the same pier used for mounting the theodolite in observing for azimuth. The transit foot plates being firmly attached to the stone pier, it was possible to always place the instrument very nearly in the meridian without any special adjustment.

The observations for azimuth were reduced by finding the azimuth of the star at elongation and applying a correction depending on the interval between the time of elongation and the time of observation. The declinations and right ascensions used were taken from the Berlin Jahrbuch.

in whice

is the interval in time from elongation to the time of observation. This was used for intervals not exceeding twenty-five minutes. For deriving the correc

tion, Table VI in Chauvenet's Astronomy, Vol. II., was used. For intervals exceeding twenty-five minutes the rigorous formula for the azimuth was used,

To the mean result for each night the correction for diurnal aberration +0.3 was applied.

In the table following the details of the results of the observations for azimuth are given:

Azimuth at observatory, Sault Ste. Marie, Mich., E. E. Haskell, observer.

[Star, date, etc.: Polaris near western elongation. March 2, 1894, a = 1h 18m 56.97 888° 44' 50".96; A. 178° 10' 48.75.]

Azimuth at observatory, Sault Ste. Marie, Mich., E. E. Haskell, observer-Continued. [Star, date, etc.: Polaris near western elongation. March 8, 1894, a = 1 18m 53.09; d= 88° 44′ 49′′.41; A. 178° 10' 45.96.]

[Star, date, etc.: Polaris near western elongation. March 14, 1894, a=1h 18m 50.76; 88° 44′ 47′′.79; A 178° 10' 44".14.]

178 06 38. 7 +0.2 178 06 39.0

Azimuth at observatory, Sault Ste. Marie, Mich., E. E. Haskell, observer-Continued.

[Star, date, etc.: Polaris near western elongation. March 14, 1894, a 1h 18m 50.76; 8=88° 44' 47".79; A. 178° 10' 44".14.]

[Star, date, etc. Polaris near western elongation. March 19, 1894, a = 1h 18m 48 .61; 8=88° 44′ 46′′. 49; A. 178° 10' 42". 25.]

Azimuth at observatory, Sault Ste. Marie, Mich., E. E. Haskell, observer-Continued.

[Star, date etc.: 51 Cephei, near western elongation. March 19, 1894. 14.15". A. 175° 57' 37".30.]

@= 6h 50m 59.82*. d=87° 13'

Azimuth at observatory at Sault Ste. Marie to A azimuth

Mean adopted azimuth at observatory Sault Ste. Marie to A azimuth.

178 06 40. 1

178 06 38.7

For the various nights the mean results are as follows: The weighted mean is obtained by weighting according to the number of results.

Azimuth of line Observatory Sault Ste. Marie to ▲ Azimuth.

The azimuth is reckoned from the south around by the west. The result of the observations gives as the adopted azimuth for the line Observatory Sault Ste. Marie to station azimuth 178° 06′ 38.87".

LATITUDE STAR LIST.

A list of 106 pairs of latitude stars has been prepared, suitable for observations at Sault Ste. Marie. It includes pairs of stars throughout the whole range of right ascension from 0 to 24 hours, and is suited for the determination of latitude at any time of the year. The list includes 81 stars from the Berlin Jahrbuch catalogue of 622 stars; 81 stars from Safford's catalogue of 2,018 stars; 6 from the Northern Boundary Survey catalogue of 500 stars; 24 from H. Romberg's catalogue of 5,634 stars observed at Pulkowa Observatory from the years 1874 to 1880, and 20 stars from the Coast Survey catalogue of 2,179 stars, report of 1876. The various catalogues are indicated by the abbreviations B. J., S., N. B., R., and C. S. The square brackets around a B. J. star [ ] indicate it is a star for which the day places are not given in the Berlin Jahrbuch. The star factors for such stars, however, are given by which the day places can be readily computed.

The following is the list of latitude pairs. The settings given have a correction for refraction applied: