AN EQUATORIAL SUNDIAL. 569 



In summer the upper (south) side of the dial is illuminated, 

 and in winter the under (north) side. 



At the equinoxes the light from the sun falls in beams 

 parallel to the sector, and does not illuminate it, but the graduated 

 rim is bevelled outwards at an angle of 45 degrees, thus securing 

 a satisfactory shadow of the wire all the year round. 



The instrument was constructed by Mr. T. R. Miller, 

 mechanician at the Royal Observatory, to designs by the writer. 

 It should serve as a model for dials, which would be more 

 accurate timekeepers than ordinary clocks, in isolated stations 

 away from the telegraph. 



Liquid Hydrocyanic Acid for Fumigation — 



In the Report of the Pretoria Session (191 5) of the South 

 African Association for the Advancement of Science, pp. 95, 96, 

 Mr. C. W. Mally announced that he had employed liquid hydro- 

 cyanic acid for fumigating fruit trees with considerable success 

 by means of a small experimental appliance, and that larger 

 apparatus was being arranged with a view to production of a 

 sufficient quantity of the liquid acid for field trials. Mr. Mally's 

 trials of this improved method of fumigation took place during 

 May and June, 191 5, and it is now stated by R. S. Woglum, in 

 the Journal of Economic Entomology, that in the early spring of 



1916 Mr. W. Dingle, of Los Angeles, California, began public 

 demonstrations of the same method in connection with citrus 

 trees. The advantages of the method as described by Mr. Mally 

 have soon made themselves obvious to horticulturists in the 

 United States, for Mr. Woglum states that during the sea.son of 



191 7 approximately 540,000 lb. of solid sodium cyanide were there 

 converted into liquid hydrocyanic acid for the use of 30 fumiga- 

 tion outfits. In 1918 more than one million ix)unds of sodium 

 cyanide were similarly treated for the use of 94 fumigation crews, 

 and a very much greater amount would have been used if it 

 could have been produced. 



A Jovian Prominence. — An observation by F. Sar- 

 gent of a bright projection on the limb of Jupiter is recorded in 

 the Monthly Notices of the Royal Astronomical Society. The 

 projection was first seen on the evening of January 16, 1919, and 

 was then of great brilliancy. Half an hour after the first observa- 

 tion it had subsided to a bright spot on the tinted equatorial zone. 

 On the following evening the spot was followed right up to the 

 limb until it seemed to project. Seven minutes later it was 

 "flickering" in and out of the limb, and in another ten minutes 

 it broke the usually even contour of the limb, then slowly sub- 

 sided, and in ten minutes more it had disappeared. The author 

 suggests that the phenomenon was a real material projection from 

 the planet's surface of dimensions great enough to render it 

 visible. 



