446 



MR. THOMAS HEELIS^S OBSERVATIONS 



The nature of the light seems to be peculiar. I always 

 noticed that when the eye had been affected by artificial 

 light, as on coming first on deck from the cabin, the light 

 of the Milky Way became clear to the eye long before that 

 emitted by the zodiacal light ; but after the eye had been 

 for a short time in darkness, the volume of light frequently 

 produced an effect which I find in my note-book described 

 as half as bright again as the sword-handle of Perseus, as 

 bright as the Milky Way in Argo, &c. I have seen it so 

 bright as to cast quite a beam of light upon the water ; 

 and on the ist April 1862, in lat. 15° i' N., long. 93° E., 

 I was able to observe it before the setting of the moon, 

 then 2*2 days old at noon at Greenwich. In spite of all 

 this, I never on any occasion failed to see Prsesepe through 

 any part of it at times when it overlaid that object, which 

 was always, when available, used as a test of the intensity 

 of the light. 



The following Table contains the results of a few obser- 

 vations made in the Mediterranean in the year 1863. It 

 should be observed that the division of the light into two 

 distinct envelopes has never been observed by me there, 

 and that the lengths and positions given are those of the 

 whole of the light visible. The Table is arranged as 

 before, the position of the ship being given at the nearest or 

 following noon. 



Table III. 



Date. 



Time. 



E. A. 



Decl. 



Length 



Lat. 



Place of Obseryation, 



1863. 

 Sept. 18. 

 Sept. 20. 

 Sept. 21. 

 Oct. 17. 



hm 



3 30 A.M. 

 330 



4 



4 A.M. 



h m 



7 35 



7 12 



8 24 

 8 4 



C 1 



25 oN. 

 22 30 

 21 

 25 



63 



70 17 

 54 5 

 84 43 



3 25* 



6t 



1 43t 



4 40 



Approaching Corfu. 

 41° 52' N., i6°52'E. 

 Approaching Ancona. 

 Off Cape de Gatta. 



* Faint, and at apex ill defined ; so that the position assigned to apex may 

 be in error in declination. 



t Apex estimated as coincident with h Greminorum. 

 \ Light verj faint and dull, definition bad. 



