TO CORRESPONDENTS. 



Mr. Watkinss " Popular Sketch of Electro-magnetism" has been 

 received for review. 



We fear that the paper on the conjoint study of Plane and Descriptive 

 Geometry is not quite suited to our Journal. M. Fayolle has our 

 thanks for his communication on the figure of the cells of the honey- 

 comb ; an extract from which will be given in our next Number. 



* # * The Editors request that all Communications intended/or immediate 

 insertion may be sent to the care of Mr, Richard Taylor, Printing Office, 

 Red Lion Court, Fleet Street, London, at furthest by the 15th day of the 

 month, or they will be too late to appear in the ensuing Number. 



PHILOSOPHICAL MAGAZINE. 



A FEW Complete Sets of the PHILOSOPHICAL MAGAZINE, 

 in 68 volumes ; recording the Improvements which have been effected 

 in the various Departments of Science, from its Commencement in 1798 

 to the Conclusion of the First Series in 3826, may be had at the Printer's, 

 at Half Price. 



APPENDIX TO DR. PEARSON'S ASTRONOMY. 

 This Day is published, in 4to. Price 10s. 6d. 



AN APPENDIX to the First Volume of AN INTRODUCTION to 

 PRACTICAL ASTRONOMY. 



By the Rev. W. PEARSON, LL.D. F.R.S. Treasurer to the Astron. Soc. 



This Appendix is intended to make the Tables in the former part of 

 the Volume available for giving results, whatever Coefficients may be 

 employed : and also contains a Catalogue of 520 Zodiacal Stars, with a 

 Table showing when their Occultations may be expected. 



Printed for the Author, and sold by Longman, Rees, Orme, Brown, 

 and Green, London. 



In 8vo. with Plates, Price 3s. boards, 



A POPULAR SKETCH of ELECTllO-MAGNETISH, or ELEC 

 TRO-DYNAMICS; with Outlines of the Parent Sciences Elec- 

 tricity and Magnetism. 



By FRANCIS WATKINS. 



Published by Watkins and Hill, 5, Charing Cross, Philosophical Instru- 

 ment Makers, and Curators of Apparatus in the University of London. 



Watkins and Hill have also published (price Is.) A DESCRIPTIVE 

 CATALOGUE of various Philosophical Instruments and Chemical Ap- 

 paratus constructed and sold by them. 



