Royal Astronomical Society. 161 



eclipse, wrote to me for an explanation of the blood-red colour of the 

 moon at 9 o'clock. 



" The sky was of unusual brilliancy, as often occurs between 

 showers ; there was a bright aurora in the north, and a most magni- 

 ficent meteor descended obliquely towards the north-west horizon 

 about the time of the central eclipse. The western margin of the 

 disc presented a rough uneven appearance at this time. What would 

 be the effect on the dark surface of the moon of extensive aurora 

 borealis on our earth ?" 



Mr. Walkey, who observed the eclipse at Clyst St. Lawrence, 

 near Collumpton, says the appearances were as usual till 20 minutes 

 to 9. " At that period, and for the space of the next hour, instead 

 of an eclipse, or the umbra of the earth being the cause of the total 

 obscurity of the moon, the whole phase of that body became very 

 quickly and most beautifully illuminated, and assumed the appearance 

 of the glowing heat of fire from the furnace, rather tinged with a 

 deep red. The above description I gave to the editor of one of the 

 Exeter papers, and some one has attempted to solve the peculiarity 

 of the appearance by speaking of the umbra and penumbra, which 

 might have been the cause of it. But such a solution has nothing 

 to do with the appearance, the whole disc of the moon being as per- 

 fect with light as if there had been no eclipse whatever. 



" Having spoken of this appearance, I was informed by one or 

 two individuals that they had seen, between twenty minutes to nine 

 and twenty minutes to ten, a very luminous appearance of the aurora 

 borealis. Now, it strikes me that the light reflected from this 

 northern effulgence might have caused the luminous appearance of 

 the moon in this part of the country at the time when it was under 

 the perfect umbra of the earth in other portions of England. 



" Many more than threescore years have passed with myself, and 

 during that period I have several times beheld an eclipse of the moon, 

 but never before did my eyes behold the moon positively giving good 

 light from its disc during a total eclipse. The phases of the moon 

 perfectly corresponded with the authorized diagram up to the period 

 of 8 h 40 m , and after 9 h 40 m to the end of the eclipse." 



In a letter to Captain Smyth, Mr. Vallack suggests the utility of 

 adopting the binocular construction in astronomical telescopes, and 

 especially in Newtonian reflectors. He has himself fitted up two 

 mirrors on this principle, and finds a considerable superiority in the 

 pair over a single mirror. Mr. Vallack, if we understand him cor- 

 rectly, proposes the following arrangement. The specula are fixed 

 in parallel tubes, and by raising the further mirror higher up in its 

 tube, and bringing the small mirror or prism nearer to the minor, 

 an image is formed considerably in advance of the tube, which may 

 be brought so near the image formed by the nearer mirror, that each 

 may be viewed at the same time by its proper eye. The partition 

 between the tubes and also the outer tube must be pierced, to let 

 the rays of the more distant mirror pass out ; by a little adjustment, 

 the distance between the images may be made to suit different eves. 



Phil. Mag. S.3. Vol. S3. No. 220. Aug. 1848. M ' 



