Notice of Guano from the Yorkshire Coast ^ ^c. 313 



at the time of the formation of the valley, and, finally, the 

 changes which the mineralogical character of the rock has 

 undergone at the points where it touches the granite.* 



Notice of Guano^ from the Yorkshire Coast, and from the North 

 Coast of Scotland. By John Davy, M.D., F.E.S. Lond. 

 and Edm. Communicated by the Author. 



The term guano seems likely to become a generic one, to 

 designate all manures composed of the excrements of birds : 

 it is thus already used in many parts of England and Scot- 

 land. 



Although, from the nature of our climate, it cannot be ex- 

 pected that the home -guano can be equal in efficacy to the 

 Peruvian and African, yet, considering that a considerable por- 

 tion of the excrement of birds is very slightly, or not at all, 

 soluble in water — and further, that it is a question whether 

 the fixed and insoluble phosphates do not perform the most 

 important part in promoting the growth of those plants into 

 the composition of which they enter — there is sufficient reason 

 that the home kind should not only not be neglected, but that 

 attention should be specially directed to it. 



With this persuasion, I purpose briefly to give an account 

 of two portions of guano which I have lately received ; for one 

 of which I am indebted to Mr Hodgson, of Ayton Lodge, near 

 Scarborough ; and for the other to my friend Professor Jame- 

 son ; the former collected on the Yorkshire coast ; the latter 

 brought from the Skerries in the Pentland Firth, procured by 

 Eobert Stevenson, Esq., civil- engineer, and Manager of the 

 Lighthouses of Scotland and the Isles. 



The Yorkshire guano, Mr Hodgson informs me, is the 

 excrement of wild pigeons, which, in large numbers, frequent 

 and breed in the limestone cliffs of Scarborough Head . About 

 forty tons of it are collected annually, by men who follow the 

 difficult and dangerous occupation of gathering eggs, and who, 

 for that purpose, let each other down, by means of a *' gin" 

 or windlass, from the margin of the cliff, varying there in 

 height from 50 to 200 feet. It is purchased by the farmers in 

 the neighbourhood, at the rate of Is. per bushel, or about 2s. 6d. 



♦ From rinstitut, No. 540, p. 154. 



