1894.] The Total Solar Eclipse o/16th April, 1893. 21 



each 1*75 in. height and 2'5 in. in base, with refracting angles of 62, 

 and the second spectroscope had one prism 2' 6 in. both in height 

 and base. 



Condensing lenses, 3'5 in. aperture and 17'5 in. focus, and of 3 in. 

 aperture and 14'5 in. focus, were used with the two instruments re- 

 spectively. 



Both spectroscopes were fixed on stout mahogany base-boards, and 

 were completely adjusted before leaving England. 



To attach them to the mounting, a mahogany tube, about 6 in. 

 square and 2 ft. long, was bolted to the top of the declination axis, 

 and the base-boards of the spectroscopes were screwed on either side 

 of it. 



A small telescope of 2^ in. aperture was attached on the other side 

 of the tube to act as a finder and for purposes of adjustment. The 

 mounting was one that was made for the eclipse of 1886. It con 

 sisted of a tripod stand composed of pieces of angle iron with the 

 polar and declination axes, and circles of the Corbett equatorial. It 

 was found to be easy to set up and rigid. 



On arrival at Fundium, a site was selected, and a concrete base 

 was formed. On this the instrument was set up, and no trouble was 

 experienced in getting it into adjustment. The slits of the two 

 spectroscopes were placed parallel to each other and tangential to a 

 circle of declination, and were adjusted so that they cut across oppo- 

 site limbs of the sun, that of the two-prism spectroscope being 

 across the upper or western limb, and that of the one-prism spectro- 

 scope across the eastern limb. For several days before the eclipse, 

 trial plates were taken, in order to obtain reference spectra, and for 

 getting the focus as perfect as possible, as well as for the sake of 

 practising the development of the plates. 



The plates used were Cadett's most rapid make, and various de- 

 velopers were tried, but no special peculiarities of behaviour were 

 noticed ; pyrogallic acid was used for the eclipse plates. Before leaving 

 England the plates were backed with a solution of asphalt in benzole, 

 for the purpose of destroying the halation or reflection from the back 

 surface of the glass. 



At the eclipse the shutters of the two cameras were opened about 

 ten seconds after the commencement of totality, and closed about ten 

 seconds before the end, giving a total exposure of three minutes 

 fifty seconds. During the progress of the eclipse I observed the 

 corona and the upper or western limb of the sun through the small 

 telescope with a magnifying power of 40. The corona in this region 

 showed very faint radial markings and several rosy-pink prominences 

 were seen. The largest of these was one at the W. N. W. limb, which 

 is the one of which a strong spectrum was obtained with the two- 

 prism spectroscope. The plates were developed the same evening on 



