LXII THE ROYAL SOCIETY OF CANADA 



feet in diameter, for the telescope. A well has been bored on the pro- 

 perty, and a pump installed to raise the water to a tank on the summit. 



Solar Observations. 



The solar rotation plates of 1911-12-13, have been measured and 

 reduced by Dr. Plaskett and will be published shortly. A summary 

 of the results was presented at the current meeting of the Society. 



Direct photographs of the sun (113 in number) were taken on 

 all suitable days when spots were present. With the 23-foot 

 spectrograph 303 plates were made. About 150 of these (1000 

 exposures) recorded simultaneously two sets of spectra of the limbs, 

 one of the centre of the Sun's disc and two of iodine comparison spectra 

 at ^ 5600. The majority of these were taken at the Sun's equator, 

 while 29 plates were made at position-angles 15° apart from 0° to 90°. 

 Plates of spot-spectra (124 in number having over 500 exposures) 

 record, for various spots in various positions, the penumbral con- 

 vection for the gases producing the spectral lines in regions from 

 A 3800 to ^ 6200. Some of the above plates have been measured, 

 though most of the time available for measurement has been spent in 

 completing the measures of the 1911-1913 solar rotation spectra. 



Photometric Observations. 



The time previously given to micrometer work with the 15-inch 

 telescope has been devoted during the past year to the mounting and 

 adjusting of the new photographic telescope. This equipment con- 

 sists of two doublets of 8-inch and 6-inch aperture and 40-inch and 

 30-inch focus respectively, a Zeiss lens of 3 • 3-inch aperture and 1 1 • 8-inch 

 focus, a guiding telescope of 4-5-inch aperture and 52-5-inch focus, 

 and two objective prisms of 15° and 25° to attach to the 8-inch 

 doublet separately or together. The whole is mounted equatorially, 

 the driving clock having both hand and electric slow-motions. 



Direct photographs and spectra of Delavan's comet were ob- 

 tained during the late summer, and in the winter the lenses of the 

 doublets were thoroughly tested for curvature of field and aberration. 

 The 6-inch proved to be suitable for extra-focal work as applied to 

 star magnitudes and, as an excellent dark-room has been provided, 

 work is now being carried on in the investigation of variable stars. 

 It is intended to extend the photometric work with this instrument 

 as well as to devote some time to direct photography of comets and 

 star fields in the Milky Way. 



