CORRESPONDENCE OF RAY. 177 



tion of tlie manna ; for I do not observe any kind of 

 gum, or resin, or concrete juice, to issue out of any tree 

 or herb but at some incision, or wound, or rift, or con- 

 tusion, and tlierefore it is likely enough that the manna 

 may issue out of the vessels containing the specific juice 

 of the tree perforated by some insect. Yoiu- other con- 

 jecture also concerning the insect preparing a kind of 

 manna is not improbable. 



Black Notley, Sept. 14, —85. 



Dr. Hans Sloane to Mr. Ray, 



Sir, — I wrote a pretty while ago to you about the 

 Hockesdon earth, which, because I fear it miscarried, I 

 now repeat, desiring your opinion of it. 



Not far from Moorfields, near the new square in 

 Hockesdon, some workmen digging a cellar for a new 

 house in the end of a garden, when they were about 

 three feet below the surface of the ground, found a very 

 strong smell in the one half thereof. Passing that way, 

 and finding it very sm-prising, and a thing that I had 

 neither heard of nor seen before, I thought it worth 

 farther inquiry. 



The workmen having dug a pit about six feet deep, 

 at about three yards' distance from that end of the cellar 

 which smelt so strong, I there found three several layers 

 of earth one over another, all of them, more or less, 

 having the same scent. The uppermost stratum was 

 clay, or, as the workmen call it, loom. It did not smell 

 till three feet deep, but then was very strong, and some- 

 thing noisome. If one look earnestly on some pieces of 

 this clay, there are easily discernible several small quan- 

 tities of a bituminous substance, brownish colour, and 

 tough consistence. I doubt not but this substance gives 



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