476 Miscellaneous Intelligence. [Oct 



taken as a distinguishing mark, will amount to many more species than I have 

 hitherto found described in any author I have been, able to consult. 



I had intended sending a drawing of the Nepa grandis, but not being able to 

 delineate it myself with sufficient accuracy, I have been obliged to delay it, until 

 I can get it drawn correctly. 



I X .-—Miscellaneous Intelligence. 



1. Roman Coins in Upper India. 

 In a letter published in the India Gazette of the 19th October, Dr. R, Tytler 

 mentions that many of the Diocletian coins noticed in the catalogue of the Socie- 

 ty's Cabinet were presented by himself, and that they were collected at Allahabad, 

 Mirzapur, and Bindcichal. His inference is, that they were brought to India by 

 Christian emigrants, during the ten years' persecution which occurred in the reign 

 of that Emperor, and that some of the doctrines of the Christian religion were 

 then engrafted upon the superstitions of Hindustan. The coins of Carinus and 

 Numerianus were from Mirzapur and Chunar : and another of Diocletian's was 

 procured at Kanouj. If diligent inquiry be made in that part of India, probably 

 an extensive collection of coins of the third century may be made. More remains 

 of the sort will naturally be discovered in the neighbourhood of ancient towns, and 

 the most prevalent date of the coin will in some way prove the period at which 

 these cities were in the most flourishing condition. P. 



2. Spontaneous Combustion of Coal. 

 On Friday, the 26th instant, smoke was observed to issue from the hold of the 

 London, one of the ships severely handled in the late storm, which on examination 

 was found to proceed from 300 tons of coals then on board that vessel. Means were 

 taken to discharge the cargo, and the river engines were kept at work for two 

 days and nights, pumping water in to swamp the ignited mass : the only damage 

 sustained was in one of the pillars of the lower deck, which was nearly burned 

 through. A portion of the coal was examined by Mr. Ross, of the Mint, and found 

 to contain a considerable portion of pyrites -. this mineral by the action of water 

 and air is rapidly converted into sulphate of iron, and developes sufficient heat, 

 when the mass is large, to ignite the coal : frequent accidents of the same nature 

 have before happened. The steamer Emulous on sailing from England was forced to 

 put back on account of the ignition of the coal stores. H. M. Ship Ajax is suppos- 

 ed also to have been destroyed in the same way. Commanders of vessels should 

 take particular care that coals taken on board are quite dry, and shew no yellow 

 veins or nodules : and they should not be placed where they are liable to be wetted, 

 nor too near the powder magazine. 



3. Transit of Mercury observed in England. 

 The 5th of May proved in England, as in India, a cloudy day. The planet was 

 seen only thrice on the sun's disc by Mr. Barker of Deptford, and then only for 

 intervals of two or three seconds : the spectacle therefore, as that observer writes in 

 the Literary Gazette, was more gratifying than satisfactory in a scientific point of 

 view. At 9h. lm. A. M. Mercury was seen advanced about half his diameter on the 

 disc. 9h. 3m. was observed to be the period of the first internal contact ; but it is not 

 mentioned whether the chronometer employed was at mean solar, or apparent time. 



