TO CORRESPONDENTS. 



We hope to have room in our next Number for Mr. Elliott's Paper on the 

 Manufacture of Oil Gas. 



The following Communications have been received, and are under considera- 

 tion : — On the Velocity of the Waves of the Sea, by Gapt. D. Thomson : — On 

 ('elestial Globes, by Mr. J. W. Woolgak :— On the Trisection of a Circular Arc, 

 by Mr. P. Newton : — On Electro-Magnetism, by Mr. Tatl'm : — On Opaque 

 Crystallized Carbon ; and, Experiments on Oil and Coal Gas, by Mr. William 

 HERAPATn : — On the Combination of Phosphorus with Sulphuret of Carbon, by 

 Mr. Murray : — and a New Theoi^ of Telescopes, by Dr. J. Rf.ade. 



We have much pleasure in informing Mr. Innes, and our astronomical readers, 

 that wc expect soon to be favoured with the third portion of the Zodiacal Ca- 

 talogue. 



Mr. L. GoMPERTZ informs us, with reference to the Paper of " VolatoHj^' 

 Oct. 18^1, that in 1813 he had made experiments with a set of pasteboard vanes, 

 A«ith a stick fixed in the middle, which being twirled in the hands, rose up several 

 feet on being let go. 



We have received Mr. Guttehidge's Reply to Mr. Wiseman, but fear that we 

 «hall not be able to find room for a continuation of the discussion. It may be use- 

 ful just to refer our readers to Mr. Farey's Paper on Timber-measuring in our 

 19th volume, p. 213, and to Mr. Bevan's work on the same subject. 



HOLMES'S AMERICA, &c. 

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 ^ A N IMPARTIAL ACCOUNT OF THE UNITED STATES; 

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[This publication will be found to contain a Compendium of the most valuable 

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3. THE MECHANIC or COMPENDIUM OF PRACTICAL IN- 

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[Upwards of two hundred of the most useful and ingenious inventions in 

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Publiehed by Henry Fisher, 38, Newgate-etreet, and sold by all Book- 



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