Ul4 REMARKS ON EXPERIMENTS. 



The following experiments are reported, either on account of 

 having been accurately made and carefully observed, or as pre- 

 senting such results as have been generally obtained on similar 

 soils, from applications of fossil shells to nearly six hundred acres 

 of Coggins Point farm (made before 1830). It had been my 

 habit to make written memoranda of such things ; and the mate- 

 rial circumstances of these experiments were put in writing at the 

 time they occurred, or not long after. Some of the experiments 

 were, from, their commencement, designed to be permanent, and 

 their results to be measured as long as circumstances might per- 

 mit. These were made with the utmost care. But generally, 

 when precise amounts are not stated, the experiments were less 

 carefully made, and their results reported by guess. Every 

 measurement stated, of land or of crop, was made in my presence. 

 The average strength of the diiferent marls used was ascertained 

 by a sufficient number of analyses j and the quantity applied 

 was known by measuring some of the loads, and having them 

 dropped at regular distances. At the risk of being tedious, I shall 

 state every circumstance supposed to affect the results of the ex- 

 periments ; and the manner of description, and of reference, 

 necessary to use, will require a degree of attention that few readers 

 may be disposed to give, to enable them to derive the full benefit 

 of these details. But, however disagreeable it may be to give to 

 them the necessary attention, I will presume to say that these ex- 

 periments deserve it. They will present practical proofs of what 

 otherwise would be but uncertain theory and give to this essay 

 its principal claim to be considered truly instructive and useful. 



When these operations were commenced, I had heard of no 

 other experiments having been made with fossil shells, except two, 

 which had been tried long before, and were considered as proving 

 the manure to be too worthless to be resorted to again. 



The earliest of these old experiments was made at Spring Gar- 

 den, in Surry, about 1775, by Mr. Win. Short, proprietor of that 

 estate. The extent marled was eight or ten acres, on poor sandy 

 land. Nothing is now known of the effects for the first twenty- 

 five or thirty years, except that they were too inconsiderable to 

 induce a repetition of the experiment. The system of cultivation 

 was doubtless as exhausting as usual at that time. Since 1812, 

 the farm has been under mild and improving management gene- 

 rally. No care has been taken to observe the progress either of 

 improvement or exhaustion on the marled piece ; but there is no 

 doubt that the product has continued for the last fifteen years 



structure and character in as marked manner as any true marl. Such 

 clays, in former times, were not distinguished by farmers, or even agri- 

 cultural writers, from marl. 1849.] 



