11 



As I before intimated, Professor Henslow was not the first to 

 •discover these nodules ; in fact they abound throughout the 

 Tertiary formations of the Eastern Counties, and had been long 

 known to geologists. Nor was he the first to analyse them ; tliii, 

 had been already done by Mr, Potter. But it is believed that 

 he was the first to see the uses to which they might be put in 

 agriculture. 



This idea was brought forward in a communication to the 

 British Association in 1845, three years after his first visit to 

 Felixstow, in which he suggested that they might take the place 

 of bones, from which the phosphate of lime used as a manure had 

 up to that time been obtained, but of which the supply of late 

 years had become insufficient. After reverting to the subject of 

 the Crag nodules, he goes on in this memoir to say that " Mr. 

 " Brown, of Stanway, had subsequently obtained several analyses 

 -" of these pebbles, and also of similar nodules obtained from the 

 " London clay (one of the older Eocene beds) in the vicinity of 

 ■" Euston Square ; and that he had found the same amount of 

 •" phosphate of lime in all, viz., 50 or 60 per cent, in each. The 

 "" Crag pebbles (he adds) occasionally contain remains of small 

 " crabs and fish, like those in the London clay, leading Mr, Brown 

 " to the conclusion that they were derived from the destruction 

 ^' of certain beds of that series. The Crag nodules were so 

 ^'abundant that a gentleman had obtained two tons of them, 

 " which after being prepared, >vere found upon analysis to 

 ^•contain 63 per cent, of phosphate of lime, 13 of phosphate of 

 "iron, and the remainder carbonate of lime and volatile 

 ■" matter."* 



Two years later (1847) Professor Henslow read a second 

 paper to the Geological Section of the British Association on the 

 subject of the Crag iiodules having been derived from the 

 London clay. He says : " he had at first considered them as of 



* Eeport of British Association, 1845, Sect. p. 51. 



