I. — Asti'onoinic Observ^ations. 



Thj expedition of H.IJ.H. was supplied with four pocket clironometers at 

 mean time, and l)efore starting on the joufuey these were kept under control 

 at the ITydrographic Institute. During this period of control, the altsolute and 

 daily corrections recorded for the s;ii(l cliioiionieters at 0'' of mean (Ireeiiwich 

 time yielded the following results : — 



After leaving Genoa, and more particulai'ly during the voyage by steamer 

 from Naples to Port Said, the chronometers were left uniegulated. But at 

 Port Said they were again set going, and on 20th April, 1906, compared with 

 the chronometer at the Police Station, in order to record their al)Solute 

 correction. 



On the 26th of the same month another comparison was effected at 

 Jibuti with the chronometer of The Eljihiiistoiw of the Indian Navy, and on 

 4th May, yet another with the chi'ononietei' of the Post Office at Momltasa. At 

 Entebbe, thanks to steps previously taken, it was found possible on 12th May 

 to make a fresh comparison by wire with Mombasa, so that by means of these 

 two comparisons was obtained a first diurnal correction of the chronometers to 

 be used in the sulisequent calculations. 



The elements of comparison ajipear in the record of the pocket chrono- 

 meters included in the present lieport. From it we find that at Mombasa, on 

 4th July, at noon, local time, there were the following al>solute corrections on 

 Greenwich mean time : 



Ki = + 3" 16- 

 K.2 = + 3 26 



K., = + 3 2 



34«- y 



9 -0 



10 -5 



C09 



