502 Sir G. C. Haughton ow the Common Nature of 



determined at both stations, the posterior slope exhibiting a rapid 

 and deep fall, which took place alike at Christiania and Plymouth. 



The crest No. 2 passed Cork, Belfast and tlie Orkneys on the 

 .5th, Plymouth on the 7th, and Paris on the 8th, with a diminution 

 of oscillation. We find however no diminution of oscillation at 

 Christiania as compared with Plymouth. It is highly probable the 

 subsidence of the crest, as it proceeded towards Paris, resulted from 

 the influence of the land in England, while both at Plymouth and 

 Christiania the crest was but slightly interfered with by the influ- 

 ence of land, the difference of level resulting from the anterior slope 

 of crest No. 3. 



These considerations exhibit a large wave of considerable breadth 

 and slow motion, extending in a longitudinal direction from the ex- 

 treme south-west of England, past Norfolk, towards the Swedish 

 capital. 



The elements of the waves, as referred to in Tables IL, III., IV. 

 and v., have been determined by observations made daily ; and a 

 perusal of the discussion of these observations will clearly show that, 

 in order to detect and examine the characters of the larger undula- 

 tions, daily observations may suffice. For this purpose it will be 

 best to choose the middle of the day. The Astronomer Royal has 

 determined, from four years' observations at Greenwich, that at 2 

 hours, Gottingen mean time (20 minutes past 1 p.m. Greenwich 

 time), the barometer varies but O'"-001 from the mean of the year, 

 that is, if the mean pressure is to be determined from an isolated 

 observation each day, this hour is the most suitable, the mean cor- 

 rection being 0"'-001 to be added. This at once indicates, that for 

 the present purpose this hour is also the most suitable, the observa- 

 tions being, to a great extent, free from the effects of the diurnal 

 oscillation. If two observations are made, the most suitable epochs 

 are 7'20 a.m. and 1-20 p.m.; and if three, 7-20 p.m. in addition. In 

 order however to detect and examine smaller undulations, observa- 

 tions at shorter intervals equally disposed througliout tlie twenty- 

 four hours are essential. 



LXXVII. Experiments proving the common natiire of Mag- 

 netism, Cohesion, Adhesion and Viscosity. By Sir Graves 

 C. Haughton, K,H., M.A., F.R.S., Foreign Associate of 

 the Institute of France, 8)C. 



[Continued from p. 457.] 



Part II. 



Of the midual magtietic attractions of non-ferruginous bodies. 



AFTER a great number of substances had been measured 

 according to the preceding plan, it occurred to me that by 

 a slight modification of the needle, the mutual magnetic rela- 

 tions of non-ferruginous bodies might possibly be ascertained. 

 Through the obliging readiness of M. Pixii of this city, I liad 



