208 Dr Hibbert on the Dispersion of Stony Fragments, 



and fixed by a rope and small block attached to it at the up- 

 per part of the stern of the boat at D. 



E, the rack and pinion work, secured by strong iron 

 plates to a thwart near the stern of the boat, consists of two 

 pinion wheels, the axes of which are horizontal, and in the 

 line of the keel of the boat ; and the lower pinion wheel is one- 

 half the diameter of the upper one, and has the universal 

 joint at F fixed to the after-end of its axis, which being united 

 to the scull in its diagonal position, and wrought by means of 

 the crank GG, fixed to the fore-end of the axis of the upper 

 pinion wheel by the two men at H, produces an increased ve- 

 locity, and accelerates the motion of the vessel. 



The paddle plates at the extremity of the axis of the scull 

 are placed at right angles to each other ; and at an angle of 

 45 degrees with the said axis or spindle, and are secured to 

 each other in that position by a strong iron strap, in the centre 

 of which there is a square aperture to receive the outer end of 

 the axis of the scull, to which it is fixed by a screw nut. 



Hermitage Hill, February 5, 1825. 



Art. V. — On the Dispersion of Stony Fragments remote 

 Jrom their Native Beds, as Displayed in a Stratum of 

 Loam near Manchester. * By Samuel Hibbert, M. D. 

 F. R. S. E. and Secretary to the Society of Scottish Anti- 

 quaries. Communicated by the Author. 



1 he important researches of Professor Buckland, on the sup- 

 posed evidence of diluvial action afforded by deposits of loam 

 and gravel, are now beginning to excite the attention which 

 they so well deserve. This geologist has proposed to separate 

 two classes of phenomena, which were previously referred to 

 one common cause. Of these, the jirst is the general disper- 

 sion of gravel and loam over hills and elevated plains as well 

 as vallies, which he conceives to be the effect of an universal 

 and transient deluge. To the gravel and loam thus said to 

 be dispersed, the name of Diluvium, in reference to their al- 

 leged cause, has been given. The second class of phenomena 



" Read before the Royal Society of Edinburgh, January 3, 1825. 



