310 Scientific Intelliyence, ^c. 



far to determine an important but disputed question in physics, viz., 

 the change in magnetic intensity at different altitudes above the 

 earth's surface. He stated briefly the results of 45 series of obser- 

 vations with Causteen's intensity needles at 13 stations in the Alps 

 and Pyrenees, from six to 1000 feet above the level of tlie sea, and 

 compared with the intensities observed in the intermediate valleys. 

 The general result at which he arrives is, that there is no general 

 decisive vindication of diminished intensity with height, at least 

 within the limits of error of the instrument, and certainly, if it 

 exists, the diminution must be exceedingly much smaller than M. 

 Kuppfer has proposed. 



6. A paper, by Sirl}. Brewster, on the action of crystallized sur- 

 faces upon light was read, and gave rise to some discussion on the part 

 of Sir W. Hamilton and Mr. M'Cullagh; but the statements of the 

 paper do not admit of abridgement. 



7. Dr. C. Williams gave an account of an improved ear-trumpet, 

 by which sounds are rendered audible at three times the usual dis- 

 tance. The Section then adjourned. 



Evening Meeting. — 8. Mr. G. W. Hall on the Connexion 

 of the Weather with the Tides. — Mr. H. observed, that the baro- 

 meter undulates at the changes of the moon, but more commonly 

 sinks than rises ; the weather is then generally unsettled, with high 

 winds; as the weather settles, it not unfrequently remains in an 

 indeterminate state. These variations apply to all the changes of 

 the moon. 



9. Mr. Ettrick on an Instrument for observing Terrestrial 

 Magnetism. — This instrument consists simply of a common Coulomb's 

 balance, substituting for the needle a magnetic bar, to which is 

 screwed a finely divided graduated circle. The degrees of deviation 

 are read off by means of a telescope with cross wires placed perpen- 

 dicularly to the plane of the circle. 



The author described and exhibited to the Section a new kind of 

 cushion ; which, being constructed of distinct pieces, and acted on by 

 springs, could apply itself to a cylindrical glass of any irregular sur- 

 face. He also described an improved rubber for the plate machine, 

 by which the author supposes an increased power is obtained ; it is 

 not very different from the form of the rubber as usually employed. 



The same gentleman described a New Instrument for trying the 

 effect of jElect7'ical Discharges in Rarefied Air, or in different 

 kinds of Gases. — He finds the bar usually observed on sending 

 a shock through a card quite uninfluenced by the state of the medium 

 in which it is placed ; it also remains the same in gases of different 

 kinds. 



10. 3Ir. Addams on the Vibratio7i of Bells. — The author, in 

 this paper, endeavours to explain a peculiar beat frequently heard in 

 the sound of a clock or tower bell, which he considers to arise from 

 unequal thickness of the metal ; this he illustrated by some striking 

 experiments on a glass bell. 



11. 3Ir. Rootseyo7i the higher order of Grecian Music, and on 

 Mnemonic logarithms. — The first of these papers relates to some 

 kinds of musical chords, rejected by some j)ersims as being ini- 



