206 On Removing of Olstnictiuns [March, 



in Norway and Germany is not applicable to the same formation in 

 Britain. 



The same species of organic remains whicli occur imbedded in 

 different strata of the floetz class, appear to have sustained the 

 shock of several revolutions before the total destruction of their 

 tribe ; and we may also suppose that part of the race of orthoce- 

 ratites survived the period of the deposition of the transition class, 

 but became at last enveloped in the beds of the coal formation. 



I cannot conclude these observations without taking notice of the 

 qreat difference in point of size between the existing species of the 

 genus orthocera and those orthoceratites which are found in the 

 mineral regions. The living species of the genus to be met with on 

 the British shores do not exceed a quarter of an inch in length, and 

 required the aid of the microscope for their examination. Only one 

 species has been found in Scotland, the 0. linearis. (Testacea, 

 Brit. Tab. 30, fig. 9.) It was found by Mr. Montagu in a parcel 

 of minute shells sent to him from Dunbar. It is only a quarter of 

 an inch in length j and its breadth is about one-eighth of its 

 length. 



Manse of Flisk, Fi/eskire. 



Article VII. 



On Deepening, Cleaning, Excavating, and Removing Ohstructions 

 that prevent Vessels from entering Harbours. By John Rook, 

 jun. of Akehead, Wigton, Cumberland. 



When we examine the force and power of water, we are con- 

 vinced that it is an engine capable of performing various powerful 

 operations. In its course from the uplands, and through the low- 

 lands, till immersed in the Ocean, it forms for itself spacious 

 channels and deep pools. When man brings its gravitating motion 

 under subjection he obtains a useful and faithful servant, that 

 performs for him numerous important labours. Passing from these 

 reflections to a new modification of the use of that element, there 

 seems to be a probability that it might be rendered useful in the 

 improvement of the entrance of harbours, &c. by means of carrying 

 it through tunnels, formed according to the circumstances of 

 situations. These tunnels or pipes might be constructed either by 

 collected materials, such as stone, wood, and metal, or formed by 

 sinking down to the rock, and directing the tunnel in it according 

 to the object in view. The use to which I would apply the 

 principle is that of passing through these tunnels or pipes as 

 powerful a stream of water as could be obtained ; by which means 

 considerable quantities of sand, gravel, &c. might be removed bv 

 the violent stream of water issuing forth from its confined channel. 



