Total Eclipse of the Sun, 1901, May 18. 23! 



"Total Eclipse of the Sun, 1901, May 18. Preliminary Account 

 of the Observations made at Pulo Aoer Gadang, West 

 Coast of Sumatra." By F. W. DYSON, M. A., F.RS., Sec. RA.S. 

 Received October 24, Read at Joint Meeting of the Royal 

 and Royal Astronomical Societies, October 31, 1901. 



I. General Arrangements. 



The Admiralty having approved of expeditions from the Royal 

 Observatory to observe the Solar Eclipse of 1901, May 18, I was 

 instructed by the Astronomer Royal to occupy a station on the 

 West Coast of Sumatra with the instruments used at Ovar in the 

 eclipse of 1900, May 28. Mr. J. J. Atkinson, who accompanied the 

 Observatory expedition to Ovar, again generously volunteered his assist- 

 ance and is associated with me in all the observations. His advice and 

 co-operation were of the greatest value throughout. 



The programme of observations, which was arranged in concert with 

 the Joint Permanent Eclipse Committee, was essentially the same as 

 that carried out at Ovar. 



The 16-inch ccelostat and the 4-inch rapid rectilinear (Abney) lens 

 were lent by the Royal Astronomical Society, and Captain Hills 

 kindly lent the spectrosopic equipment he used at the Indian eclipse, 

 viz., a two prism flint spectroscope, a four prism quartz spectroscope, 

 and a 12-inch heliostat. 



At the request of the Royal Society the Admiralty placed 

 H.M. gunboat " Pigmy " at the service of the observers in Sumatra. 

 We are indebted to Lieut, and Com. Oldham for the ready manner in 

 which he assented to our request to anchor off Gadang, and let us 

 live on the " Pigmy." Without his cordial co-operation this station 

 could not have been occupied. We are further indebted to him and 

 to the officers and men of the " Pigmy " for assistance in erecting the 

 huts and instruments, and for the large share they took in the 

 observations on the day of the eclipse. 



We received every assistance from the Government of the Dutch 

 East Indies in the choice of station and arrangement with the natives, 

 and were given free passes for ourselves and instruments on the railways. 

 We are specially indebted to Mr. Joekes, the Governor of the West 

 Coast of Sumatra, to Mr. Von Locken, the Assistant Resident at 

 Painan, to Major Miiller, the Director of the Ordnance Survey and 

 Chief of the Dutch eclipse party, and to Mr. Delprat, the Director of 

 Railways. 



Itinrmri/. The observing huts and instruments having been 

 despatched some days previously, the 16-inch ccelostat mirror and 

 some of the photographic plates were taken to Southampton and put 



