^ TO COUKESPONDENTS. ^f 



V^ J. B. Emmett's Coinmunications have been received, as have ^*' 



^ also ^Mr. Pater's a^.id Mr. Dodd's. ^ 



M A number of other Communications have been rcccivfed for Z. %r^ 



I' and forwarded. ~ \^ 



vfi? %* Commiinicaiions for this Work, addressed to the Ediior, Jii* 



^ PcV'^rt- Place, Temple Bar, will meet with every attentimi. j|* 



Just published. Price 2s. 



OBSERVATIONS on GAS LIGHTS ; being an Inpardal Inqui-y 

 concerning the injurious Effects on the Kealth of the Communty 

 from theUse of Coal-Gas for Lighting the Metropolis, 



By CANDIDUS. 

 Published by T. and G. Underwood, 32, FLet- Street. 



»— "1 ■••■■ ■■ '■ : ■ ~,"^^ 



This Day is published, Octavo, Pric; €s, 



AN ESSAY ON THE VARIATION OF THE COMPASS, 

 showing how far it is influenced by a Change ii the Direction 0' the 

 Ship's Head, with an Exposition of the Dangers nising to Navigitors 

 from not allowing for this Change of Variation. Illjistrated with practical 

 Observations and Remarks. 



By V^ILLIAM BAIN, Mastkr, RcYAL Navy. 

 ' Printed for W. Blackwood, Edinburgh ; and John Murray, Bookseller 

 to the Admiralty and Biard of Longitude, London. 



ENGRAVINGS. 



Vol. XLVII. Illustrated with a Quarto Plate describing the Plani' 

 SPHERE of DiiNDERA.— A Ouarco Plate to illustrate Mr. Brown's Paper 

 on Architecture. — A Plate to ■ illustrate Sir George Cayley's Paper on 

 Aerial Navigation; 'and Mr. London's Hydrometer.- — A Quarto Plate 

 of the Temple of Kournou at Theoes. — A Plate of the utw Baths at 

 Ramsgate. , 



Vol. XLVIII. A Quarto Plate of the Strand or Waterlv.o Pi'-dge erected 

 over the Thames at the Savoy, London. — A Quarto. Plai.0 to illustrate 

 Mrs. Iebetson's Anatomy o\ Vegetable^.-r- A Quarto Plate to illustrate 

 Mrs, Ibbetson's Paper on the Physiology of Vegetaiilcs. — A large Quarto ' 

 plate to illustrate Mrs. Ibbetsok's Paper on a new View of Vegetable Life. 

 — A Quarto Plate to ihustrate Mrs. Ibbetson's Paper on the Physiology 

 of Vegetables ; and Mr. Mornay's Mass of Native Iron found In Brasil. 



Vol. XLIX. A Plate to illustrate Dr. Evans's Communication on 

 Terrestrial Magnetism; a new Electro-atmospherical Instrument; and 

 Mr. Andrkw Horn's Paper on yision.---A Quarto Plate to illustrate 

 Mrs. Ibbetson's Physiology of Vegetables. — A Plate , to illustrate the 

 Solar Spots which appeared during the Year 1816; — and Mr, Beyan'r 

 Improvement on the Sliding-Rulc. 



