NO. 6.] INTRODUCTION. CHRONOMETERS. XIX 



Longitude, and Rate of Chronometers. 



The expedition was equipped with 3 Mean Time chronometers : Kutter 

 24, belonging to the ship, Hohwu 639 lent by the University Observatory in 

 Christiania, and Iversen 961, lent by the maker, Mr. Iversen in Bergen. A 

 fourth box chronometer, Frodsham 3555, lent by the Norwegian Meteorologi- 

 cal Institute, was regulated to Sidereal Time some time before the departure 

 and began with a small losing rate, which, however, continually increased 

 during the first winter, and reached the inconveniently large value of between 

 5 and 7 seconds a day. It was not used for the observations of stars but 

 only for some magnetical observations, and served for the daily comparisons 

 by coincidences. These four chronometers will be designated in what follows 

 by Kt, Hw, Iv and Fr respectively. 



There were also on board a number of pocket chronometers and watches, 

 one of which was always used for the astronomical observations and com- 

 pared with Hw, generally before and after each observation. The observation 

 watch was also compared daily with Hw at the time of comparison for the 

 box chronometers. 



The box chronometers were placed on two shelves in Lieut. SCOTT-HAN- 

 SEN'S cabin, Htv and Fr only 16 cm., Kt and Iv 60 cm. above the deck. A 

 thermometer which was placed in the lower shelf with the bulb 17 cm. above 

 the deck, was read off at the time of the daily comparisons. In the same 

 cabin was also a thermograph, 80 cm. above the deck, which was working 

 almost continuously from 1893 July 5 to 1896 August 10. The thermograph 

 was compared daily with a thermometer placed by its side and with the thermo- 

 meter in the lower chronometer shelf. By means of this last comparison and 

 the daily reading of the thermometer in the shelf, which can be compared 

 with the thermograph-sheets for the same time, the mean temperature of the 

 two lower chronometers can be determined with sufficient accuracy. 



Between the last Time Signal from the Christiania Observatory received 

 at Vardo 1893 July 19 and the first after the return, received at Tromso 

 1896 August 23, a good many observations were taken which can be used 



