322 Intelligence and Miscellaneous Articles. 



a thunderstorm passed over Cheshire on the evening of the 6th inst. 

 The brush discharge, seen by Captain Briggs to issue from various 

 parts of the ship, indicates a negative charge, either in the surround- 

 ing atmosphere or in the snow-flakes which were falling thickly at 

 the time. • I a m, Gentlemen, 



Yours truly, 

 Royal Institution, E. Frankland. 



March 17, 1866. 



" On the morning of the 7th inst. we fell in with a heavy snow- 

 storm off the Isle of Man, which lasted for three hours. During this 

 time the steamer which I command exhibited the following pheno- 

 menon — a blue light at each mast-head, and also one from each gaff- 

 end. Presently one was seen on the stem-head, and, being easily 

 accessible, I had the opportunity of closely examining it. I found 

 that the light, which appeared large at a distance, was made up of a 

 number of jets, each of which expanded to the size of half-a-crown, 

 appeared of a beautiful deep violet colour, and made a slight hissing 

 noise. Placing my hand in contact with one of the jets, a sensible 

 warmth was felt, and three jets attached themselves to as many fin- 

 gers, but I could observe no smell whatever. The jets were not 

 permanent, but sometimes went out, returning again when the snow 

 was heaviest. This was from 1 to 3 a.m. At daylight I carefully 

 examined the place, but no discoloration of the paint was to be seen. 

 The stem in this part is wood, with iron plates bolted on each side, 

 and it appeared to me that the jets came out between the wood and 

 iron. The barometer stood at 29' 10 in. The ship is an iron one, 

 but I did not observe any alteration or other effect upon the com- 

 passes. I have seen the same phenomenon abroad, but never before 

 in these latitudes." 



HISTORICAL NOTICE IN REFERENCE TO THE RETARDATION OF 

 THE EARTH'S VELOCITY OF ROTATION. FROM A LETTER AD- 

 DRESSED BY PROFESSOR FICK IN ZURICH TO PROFESSOR POG" 

 GENDORFF. 



Some time ago, during a discussion on several points of the me- 

 chanical theory of heat, the question was mooted as to who was the 

 first to assert that the velocity of the rotation of the earth must be 

 retarded by the action of the sun and moon in producing tides. I 

 have found that the priority in this respect does not belong to any 

 living philosopher*. Kant developed it clearly and completely in a 

 short essay which appeared in 1754, under the title " Investigation 

 of the question which has been set for a prize for the current year 

 by the Royal Academy of Sciences at Berlin, Has the earth under- 

 gone an elongation in the length of its axis ? " This paper is in 

 volume viii. of Hartenstein's edition of Kant's works, published at 

 Leipzig in 1838, by Modes and Baumann. 



* It is commonly assumed that Mayer first expressed this idea in 1848, 

 n his essay ' On Celestial Dynamics.' Compare Phil. Mag. S. 4. vol. xxv. 



