Proceedings of the British Association. 231 



order to estimate the effect of temperature, otherwise the probable 

 error was found to be much within the limits of the errors of ob- 

 servation. — Prof. Forbes dissented from these statements, and said 

 that it was at his request Mr. Broun brought forward these results, 

 which he considered to possess much value. 



1 On the Connection between Magnetic Variation ; with certain 

 peculiarities of the Earth's Structure,' by S. M. Saxby.— Mr. Saxby 

 was of opinion, that it will be found on examining the direction of the 

 various mountain ridges of the globe, that there is a remarkable 

 angular coincidence between such line of direction and the local 

 curve of equal magnetic variation, the one crossing the other at 

 angles of from 65° to 70°. This observation applies not only to 

 extensive ridges of high land, such as the Alps, Carpathians, Andes, 

 &c, but also to submerged mountains, the tops of which form 

 chains of islands ; and it is remarkable that in the Eastern archipel- 

 ago, where we find extensive ranges of islands at right angles to each 

 other, the coincidence alluded to is apparent, and it may be asserted, 

 that the known globe affords no instance in which a general line 

 of mountain ridge deviates more than two or three degrees from 

 the above named angular coincidence. It might be interesting to 

 notice the position of mineral veins in mountainous districts in 

 connection with the above remark. There is also reason to suspect 

 that the tracks of hurricanes, typhoons, tornadoes, and excessive 

 elementary disturbances, approximate to the curves of magnetic 

 variation. 



Prof. Forbes could not assent to the views proposed by Mr. Saxby, 

 and said that the most ordinary acquaintance with the effects of 

 mountain chains on the magnet would be sufficient to show their in- 

 correctness. , 



* On the Strength of Stone Columns, by Mr. E. Hodgkinson. — The 

 columns were of different heights, varying from 1 inch to 40 inches ; 

 they were square uniform prisms, the sides of the bases of which 

 were 1 inch and If inch, and the crushing weight was applied in 

 the direction of the strata. From the experiments on the two series 

 of pillars it appears, that there is a falling off in strength in all 

 columns from the shortest to the longest ; but that the diminution is 

 so small, when the height of the column is not greater than about 1 2 



2 H 



