PERSISTENCE OF .XRSENITE. 32g 



extending over three seasons, to conclude that farmers have 

 iK)tliing whatever to fear from the small amovmt of arsenite of 

 soda in the form of house-fly bait that may accumulate in stable 

 manure. 



My sincere thanks are due to Dr. C. F. Juritz and Mr. D. C. 

 Crawford for their kind co-operation in making the analyses 

 recorded above, and to Mr. C. P. van der Merwe for his a<^sist- 

 ance in connection with the plot experiments. 



Division of Entomology, 



Department of AoRicuLTrRE, 

 Capetown. 



NOYA AQUILil^. — According to Hanxird Collcc/c Obser- 

 vatory Circular, No. 208, the first record of the star now known 

 as Nova Aquil?e is on a photogra])h taken at the above obser- 

 vatory on May 22, 1888, when its ]:»hotographic magnitude was 

 10.5. It was found on 405 subsequent ])hotographs, extending 

 over the intervening 30 years up to June 3. 1918. and in all these 

 its brightness remained practically tmchanged. In three photo- 

 graphs taken on June 7, 1918. it was of the sixth magnitude. 

 On tlie following night, when its visual magnitude was 0.8, it 

 was discovered independently l)y several persons. The earliest 

 observation ai the new star, under these circumstances, appears 

 to have been made by Prof. Laskovski at Geneva on June 7. at 

 ■9.45 p.m.. mid-European time. The star was then white, 

 and. although less bright than Altair (magnitude 0.9), was 

 ibrighter than a Ophiuchi (magnitude 2.T ). Mr. Harold Thom- 

 son, who independently detected the star on June 8, estimated 

 its magnitude on that date as 0.7, and records that on the two 

 succeeding days its brightness had increased to -0.26 and 

 -0.25 respectively. On June 9 the nova was brighter than 

 Vega, but by June 18 had faded to second magnitude, and five 

 days later it had become a third magnitude star. On July 14 

 it was of (fourth magnitude. In the visible spectrum the most 

 prominent features were the bright lines of hydrogen, while a 

 band in the blue near A 464 was very conspicuous. l)rightening 

 continuously from the time of its first a]>pearance on June 13. 

 By the end of June the star had assumed a brick-red colour. 

 During the succeeding fortnight the spectrum (^f the star showed 

 continuous approach to the nebular stage, the nebular lines 

 increasing in intensity concurrently with a reduction in intensity 

 of the hydrogen lines. From the noted dis])lacements of the 

 lines a relative velocity of 2,300 kilometres per second was in- 

 ferred — far greater than that observed in any previous nova. 

 Father Cortie records that for a few moments on July 13 the 

 star a])peared double. " This," he adds, " may be an illusion, but 

 is noted in case any other observer has seen the star double." 



