126 H. J. Rainey — Sedimentary deposit in Sailstones. [Mat, 



What struck me as being especially remarkable about these stones was 

 that when melted they left a sedimentary deposit of a yellowish-brown 

 substance. I found this to be the case at first on placing these stones in a 

 glass of water. Thinking, however, that this powdery substance may have 

 been contained in the water in which I put the stones, or that some earthy 

 matter had adhered to the stones on their falling on the ground, I carefully 

 washed some more stones in clear and pure water, and placed them in a 

 clean glass, and again there was a similar deposit. I then drained off the 

 water, and kept the substance there, with the intention of the next day 

 drying and preserving it, in view of having it eventually analyzed ; but, 

 unfortunately, it was thrown away by accident, and has therefore been lost. 

 I have never previously observed this peculiarity in hail-stones ; and as it 

 may not be generally known, I have thought it worth while noting down 

 the fact. 



It would be interesting to know, if hailstones have been regularly 

 analyzed before, what are their constituent parts,* and whether they vary 

 at different times and places, or not ? They appear to have a chemical 

 effect on vegetables, particularly on banana and plantain trees (Musa sapa- 

 lientum et M. paradisiaca,) as they become yellow and seared soon after 

 a fall of hailstones. Even grass on which hailstones have fallen becomes 

 affected in the same way, and contrary to what a shower of rain produces. 

 However, all these changes may be due simpl}'- to the low temperature of 

 hailstones. But it cannot in any way account for the sedimentary de- 

 posit, which is deserving notice and attention. 



The Presideis't said, it was unfortunate that the deposit from the hail- 

 stones had not been examined microscopically. Atmospheric dust had 

 proved in various cases to contain rather singular constituents, such as 

 diatoms, and recently some blackish powder obtained from melting snow in 

 Sweden had been found to contain iron and a percentage of nickel, and was 

 probably of meteoric origin. 



2. The Application of FhoiograpJiy to the Reproduction of Maps, Plans ^c.y 

 hy the Photo -mechanical and other processes. — By Capt. J. Watee- 

 HOUSE, B. S. C, Assistant Surveyor General of India, 



(Abstract.) 

 This paper opens with an introduction in which a short account is 

 given of the rise and progress of the system of reproducing maps and plans 

 by photography in the Ordnance Survey Office, Southampton, and in India, 

 and of the objects and advantages to be gained by it. The preparation of 

 the original and the production of the negatives is next considered, and then 

 follows a general review of the various photographic processes employed for 



* Eain.- water is known to certain carbonate of ammonia. H. J. E. 



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