BRITISH ASSOCIATION FOR. THE ADVANCEMENT OF SCIENCE. 57 



of both is found at the same hour of -westerly disturbance — viz., 1 a.m. The fre- 

 quency of the aurora, also, and the amount of westerly deflection of the magnet 

 also accord ; whilst on the other hand the auroral hours appear to have little or 

 nothing in common with the turning hours or the progression of the easterly de- 

 flections. When Sir John Franklin was going out on the expedition which de- 

 prived his country of the invaluable services of himself and his brave companions, 

 he had been furnished by the Admiralty both with instruments carefully adjusted 

 and compared with standard, and with full instructions for their use, and for the 

 mating and recording hourly observations of the utmost importance in the several 

 stations he might occupy in these seas ; and in the last letter which had ever been 

 received from him, he had expressed his determination to put up those instruments 

 at the several stations at which he should winter. 'No^v when his ardour in these 

 pursuits and that of Capt. Crozier, the second in command, and tlie other oiSeers, 

 were taken into account, there could remain no doubt that such observations had 

 been made and recorded, and that these records still existed in some of the places 

 he had last been in. When he (General Sabine) was with Capt. Parry, in 1818, 

 they had made observations with the pendulum for determining the figure of the 

 earth, and others of great scientific importance, on their way towards Behring's 

 Straits. They had been exposed to considerable risk of the ships being lost, and 

 were about to take to the boats and proceed overland, and in preparation for this 

 they merely prepared to carry with them abstracts of the observations, leaving the 

 original full records safely deposited in secure cases in the cabins of the ships, to 

 be found by those who doubtless would be sent out to look for them. He had, 

 therefore, no doubt that if the ships ef Sir John Franklin were still in existence, 

 in their cabins 'were to be found those scientific treasures ; and this was one of the 

 reasons why men of science were so anxious to have the ships carefully looked for, 

 and it was a sacred duty even to the memories of those who had sacrificed their 

 lives in procuring such results, to do them the justice and honour of having them 

 recovered if possible. 



ON CERTAIN PLANETARY PERTURBATIONS, AND ON A NEW PERTURBATION ON ENOKE's 

 COMET. — BY THE REV. W. E. PENNY. 



It appears that there are in the motions of several of the planets inequalities 

 arising from the product of the disturbing forces of two planets, which inequalities 

 appear not to have been noticed hithorto, unless very lately, but which seem to be 

 much larger than might have been expected, OAving to the length of time during 

 which they are accumulating. The most remarkable is one which exists in the 

 motions of Mars and the Earth. Its period is about 1,800 years, or about twice 

 that of the long inequality of Jupiter and Saturn. In the case of the Earth it ap- 

 pears to amount to about VJ seconds, and is owing to the product of the disturb- 

 ing forces of Jupiter and Mars, and in the case of Mars it seems to amount to 

 about 45^ seconds, and is owing to the product of the disturbing forces of Jupiter 

 and the Earth. It arises from the fact, that 4 times the mean motion of the Earth 

 is very nearly equal to 8 times that of Mars minus 3 times that of Jupiter. Its 

 value for the Earth is represented by the following equation: — S0=7"293" sere 

 (8w it— 4?i <— 3w< +Se— 4e— 3e +75°-14') ; and for Mars by the equation: — 



3 2 4. 3 2 4 



50 = - 45 684" sin (8w t—in t—on f +Se ~4e — Se +'73°-34') : where n , n , n , 



3 S2432 1 234 



