Report on tlie Solar Eclipse Expedition to Ghoglee. 23 



and that of his son, Mr. Edward Lugard, Executive Engineer, Bhun- 

 dara, a station was finally selected on the last day of the year, close 

 to the village of Ghoglee, 16 miles north-west of Nagpur, and about 

 2 statute miles south-east of the line of central eclipse. On New 

 Year's Day I observed the sun for latitude, time and azimuth, and on 

 the 2nd January we began our camp life, having lived meanwhile at 

 Kalmeshwar, in a bungalow belonging to the Department of Works, 

 three miles distant, on the way to Nagpur. We found the large 

 double tent provided by the Government most comfortable. It was 

 pitched beside a grove of mango trees, under which was a large 

 well with a plentiful supply of water. On the 4th January concrete 

 foundations were begun for the fixed mirror and lens, for the plate- 

 carrier of the long-focus telescope, and for each of the two equa- 

 torials. The latter were placed in line with the dark room of the 

 horizontal tube, so as to bring the observers within earshot of the 

 metronome which was used to regulate the lengths of the exposures. 

 It is needless to give particulars respecting the adjustments of the 

 equatorials, which were considered sufficiently accurate when within 

 two minutes of arc of the truth. 



The method pursued with the horizontal telescope was as follows : 

 With the theodolite placed on the proposed centre line of the tube, 

 the azimuth of a distant tree was found from observations of the 

 sun, and also of the pole star. Two sets of footholes for the theodo- 

 lite were made in blocks of cement at different levels, but referred 

 to a common centre. By this means the theodolite could be used 

 either as a collimator looking through the lens of the long telescope, 

 or as a directing telescope to bring the tube, lens, and plateholder 

 exactly into the required line. The fixed mirror was roughly 

 adjusted as regards azimuth with the theodolite and a reflecting eye- 

 piece, and as to inclination by means of a gauge and spirit level. 

 The final adjustment was given by slightly turning the slow motion 

 screws of the mirror until the sun's image ran along a parallel of 

 declination drawn on the cover of the plate-holder, and also crossed 

 one or other of a set of vertical lines at a given computed time. The 

 tube being set exactly horizontal, the plate-holder was " squared 

 on " by viewing the image of the object glass in a mirror held 

 against the plate-holder in reversed positions. The long-focus 

 object glass was " squared on " with the help of one of the little 

 centering telescopes originally designed by Fraunhof er. The inclina- 

 tion of the slide on which the plate-holder ran was found from the 

 computed altitude and azimuth of the sun's centre two minutes 

 before and two minutes after mid-totality. The same data also gave 

 the speed at which the plate had to move in our case 1*872 inch per 

 minute. No provision was made to counteract the very slight effect 

 of the rotation of the sun's image during the period of exposure. The 



