Total Solar Eclipse of 1.901, May 17-18. 

 3. Time Observations. 



213 



From the top of a small hillock within two minutes' walk of the 

 instruments we could see the camp of the Boston expedition near 

 Sawah Loento, at a distance of 2*7 miles (measured on the Survey 

 maps 1 : 20,000). Professors Burton and Hosmer were so kind as to 

 make an arrangement by which we received time signals and so de- 

 termined the errors and rates of the chronometer and watch which I 

 had brought with me. Professor Hosmer had a white time-ball fixed 

 that could easily be seen against the dark background of the tropical 

 foliage with the help of binoculars ; and it was arranged that on any 

 day that we hung out a signal (three white flags) in the early morn- 

 ing, he would if possible drop the time-ball at ll h 5 m s , again at 

 ll h 6 m s and at ll h 7 m s . His time observations for determining 

 the errors and rates of his own chronometers were made with a 

 2^-inch portable transit and chronograph. Mr. Hosmer gave me 

 signals on four days between the 9th and 19th of May. My watch 

 an excellent one by Frodsham, made for the 1862 Exhibition was 

 kept in exceptionally favourable conditions for good time-keeping, and 

 its rate deduced from signals received on May 9 and 16 was + 4'6 seconds 

 per diem, and from May 16 and 19 was + 4'6 seconds per diem. 



The rate of the chronometer (by Crisp) was found to have changed 

 from + O s> 7 between the 17th and 18th to + 2 s - 1 between 18th and 

 19th, the chronometer having been moved in and out of the hut 

 several times for the preparatory rehearsals. 



The following are the times of contacts observed, those predicted 

 from the elements given in the ' Nautical Almanac ' being given for 

 comparison and position-angles of the contacts being also added for 

 convenience of record : 



First contact was observed by me through the declination theodo- 

 lite, the time of my call " Now " (possibly 5 seconds late) being noted 

 on the Crisp chronometer by Lieutenant Briggs. Second and third con- 

 tacts are those for Dr. Wallace's signal " Go " at beginning of totality 

 when he was observing the disappearing current on the focussing 

 plate of the Dallmeyer telephotographic camera (image of sun T43 

 inches in diameter) and for my signal " Now " given to Lieutenant 



