590 Royal J stronomical Society: — Mr. Airy on the 



as Darlington. A glacier descending northwards from the Fell 

 would, on the contrary, carry with it. Dr. Buckland says, blocks to 

 the village of Shap, and strew them thickly over the space where 

 they are now found ; another, taking a southern course, would 

 drop the boulders on the hills and valleys over which the road de- 

 scends by High Borough Bridge to Kendal ; and a third great gla- 

 cier, proceeding eastwards betwixt Crosbj', Ravensworth, and Orton, 

 would cross transversely the upper part of the valley of the Eden, 

 near Brough, and accumulate piles of ice against the opposite escarp- 

 ment until they overtopped its lowest depression in Stainmoor 

 Forest, and disgorged their moraines into the valleys of the Greta 

 and the Tees. There are abundant proofs. Dr. Buckland states, of 

 the existence of this glacier in large mud and boulder moraines, in 

 the ascent of the gorge between Shap Fell and Birbeck Fell, and in 

 the furrows and striae, as well as the mammillated forms of the 

 rocks at the portals of the gorge, particularly on the northern side. 

 In the physical structure of this neighbourhood. Dr. Buckland 

 points out other conditions which would have facilitated the accu- 

 mulation of glaciers, as the lofty mountains of Yardale Head, which 

 overtop Shap Fell on the north-west, and the still higher mountains 

 to the west, whose snows must have nourished enormous glaciers ; 

 and he concludes by stating that Professor Agassiz, during an inde- 

 pendent tour, arrived at similar conclusions respecting the mode by 

 v.-hich the Shap boulders were distributed. 



KOYAL ASTRONOMICAL SOCIETY. 



[Continued from p. 156.] 



March 13, 1840. — The following communications were read : 



On the Regulator of the Clock-work for effecting uniform Move- 

 ment of Equatoreals. By G. B. Airy, Esq. Astronomer Royal. 



The subject of this communication is a mathematical investigation 

 of a mechanical problem of great importance in practical astronomy. 

 The author remarks, that the accuracy given to a most delicate and 

 valuable species of observations, by the use of clock-work attached 

 to equatoreals, is so great, and the importance of the application so 

 evident, that any investigation which assists in elucidating the prin- 

 ciples on which such apparatus should be constructed, and especially 

 any which points out the nature of one important defect to which 

 it may be liable, cannot but be regarded as interesting to the prac- 

 tical astronomer and the instrument-maker. 



After adverting to the different methods of giving motion by a 

 train of wheel-work to the polar axis of the equatoreal, which have 

 been adopted in the principal instruments hitherto erected, as the 

 Dorpat telescope, the Kcenigsberg heliometer, the Cambridge equa- 

 toreal, &c., the author proceeds to consider the various means 

 which have been put in practice for effecting the regulation. In 

 the mountings constructed by Fraunhofer, the axis of the regulator 

 is vertical ; it carries a horizontal cross-arm, to the extremities of 

 which are attached springs nearly transverse in direction to the 



