396 Messrs. W. H. M. Christie and F. \V. h\>,.n. 



but there is no reason to suppose that it interfered seriously with the 

 observations. 



The first contact occurred at 2 h 6 m 20' Lisbon Mean Time, and was 

 observed by Mr. Christie on the ground glass of the coronagraph. The 

 time of commencement of the total phase was not accurately noted ; 

 the duration was observed (by means of a stop-watch) and found to be 

 84 sees., during which the programme detailed below was carried out. 

 After totality photographs were" taken for orientation. The fourth 

 contact was at 4 h 36"' 13" Lisbon Mean Time. There was a good deal 

 of light during totality, the diminution of light being similar to that 

 occurring during a heavy thunderstorm in summer. The temperature 

 fell about 8 during the eclipse. 



During totality Mercury and Venus were seen, Mercury especially 

 being very brilliant. The observers had not much opportunity of 

 observing the attendant phenomena of the eclipse, and with the assist- 

 ance which was kindly given them were only just able to provide 

 adequately for the working of the instruments. 



II. Photographs of the Corona. 



The programme of observations was composed of two distinct 

 parts: 



(1.) Photographs of the corona on a large scale to show structural 

 detail. 



(2.) Photographs on a smaller scale with rapid lenses to show the 

 coronal streamers with the greatest possible extension. 



(1) Large-scale Photographs. 

 (These were taken by Mr. W. H. M. Christie.) 



The instrument used for (1) was the Thompson photographic tele- 

 scope, with object-glass of 9 inches aperture and 8 feet 6 inches focal 

 length, belonging to the Royal Observatory, in combination with a 

 concave telephoto lens by Dallmeyer, of 4 inches aperture and 16 

 inches focus, fitted as a secondary magnifier, to give an image of the 

 Sun 4 inches in diameter, with a field (for full pencils) of 14 inches 

 diameter. The total length of the coronagraph was 12 feet the 

 equivalent focal length being about 36 feet. A coelostat with 16-inch 

 plane mirror (made by Dr. Common) was employed to reflect the rays 

 into the coronagraph, which was mounted (on boxes filled with stones) 

 so as to point to the mirror at an angle of depression of about 5", and 

 at an azimuth of about 56 West of South for the day of the eclipse. 

 The camera was furnished with five plate-holders to take 15 x 15 inch 

 plates, or for the shorter exposures 12 x 10 inch plates in a carrier. 



The five slides for photographs of the corona during totality were 



