in North- Eastern America. 



15 



pure geology. A similar analysis of other examples will indicate 

 other causes of similar change ; and I think these causes ought 

 now, in reference to the specialities of each country, to be made 

 the subject of critical study and examination. Tiie problem in 

 each case to be solved is this. Given a certain geological struc- 

 ture, which indicates generally, and generally produces, certain 

 agricultural capabilities ; to what extent and in what localities 

 have these indications been interfered with and modified by 

 other agencies ? In what way and to what extent have climate, 

 physical structure, recent changes of physical structure, the 

 neighbourhood of unlike geological formations, the action of 

 those influences which produce what geologists call changed or 

 metamorphic rocks, or other natural causes, been instrumental 

 in producing such modifications ? This, like all other more ad- 

 vanced inquiries, is more complicated and difficult than the 

 simple problem of the direct relation between the character and 

 age of a rock, and the quality of the soil it produces when broken 

 up. But it will result in furnishing us with special surface 

 maps, which will be of direct and immediate use to the practical 

 agriculture of every country. And, what will be not less in- 

 teresting, theoretically, it will at once connect these soil-maps 

 with our strictly-geological ones, through the intermediate agency 

 of physical causes, similar to those which have operated in a 

 greater or less degree at all geological epochs. 



II. — Experiments with Nitrate of Soda^ Guano ^ 8fc. 

 By Lieut.-Col. Sir J. M. Tylden. 



To Mr. Pusey. 



Sir, — I was so much struck w^ith the importance of the experi- 

 ment detailed by you in the twenty- seventh Number of the Royal 

 Agricultural Journal for 1851, that I determined on trying the 

 nitrate of soda in the continuation of some experiments I had 

 been carrying on for the last three years with soot and guano, 

 and latterly gypsum ; and now, having read the paper from Mr. 

 Keary on the same subject, and your own article in the last 

 Number, on the Nitrate Beds of Peru, I take the liberty of 

 sending you the result of my experiments, as any trifling addi- 

 tion to our knowledge of this most valuable manure may be of 

 service in recommendino; it to ao-riculturists ; and also in con- 

 firmation of Mr. Keary' s experiments, which so fully bear out 

 the practical view you take of the great value nitrate of soda 

 must become to all eng-ao-ed in aoricultui'e. 



