TO CORRESPONDENTS. 



Mr. J. E. Gray's Zoological Notices, and Mr. Sturgeon's Experiments on 

 Thermo-magnetism, &c. are under consideration. 



We have been favoured with some interesting communications from Professor 

 Hare, of the University of Pennsylvania, which will appear in our next. 



This day is published, in 8vo, with a Plate and a new Map constructed 

 from the best authorities, price 12s. boards, 



SELECTIONS from the WORKS of the BARON DE HUMBOLDT, 

 relating to the Climate, Inhabitants, Productions, and Mines of 

 MEXICO, with Notes and an Introduction. 



By JOHN TAYLOR, Esq., 

 Treasurer to the Geological Society, &c. 



Printed for Longman, Hurst, Rees, Onne, Brown, and Green. 



This work is intended to communicate information on these interesting 

 subjects, and particularly to those who may be investing Capital in the 

 Mines of New Spain, or to others who may contemplate a residence in the 

 country. Some recent and original communications will be found in the 

 work. 



THE SECOND EDITION OF THE CAMBIST, 



Essentially improved by the aid of Government. 

 Published in two vols. 4to, price 41. 4s. in boards, 



THE UNIVERSAL CAMBIST, and COMMERCIAL INSTRUC- 

 TOR ; being a full and accurate Treatise on the Exchanges, Moneys, 

 Weights and Measures of all trading Nations and their Colonies. 



By P. KELLY, LL.D. 



Master of the Finsbury-square Academy, London; and Mathematical 



Examiner to the Trinity-House. 



The Second Edition, corrected and enlarged. 



This edition comprehends the results of the late comparison of foreign 

 weights and measures with those of England, effected for the first time on 

 a general and systematic plan by order and aid of the British Government. 



A Supplement on Indian Weights and Measures is in preparation, by 

 order of the Honourable Court of Directors. 



These volumes also contain an entire revision of foreign exchanges from 

 recent operations, and of foreign coins, from verified assays. An explica- 

 tion of the coins is added, with a translation of their legends; and the 

 work concludes with a copious index and commercial dictionary. 



Printed for the Author: and sold by Lackington and Co., Finsbury- 

 square; by J. M. Richardson, 23 Cornhill ; and by the principal Book- 

 sellers of the United Kingdom. 



Of whom may be had, by the same Author, 



An INTRODUCTION to SPHERICS and NAUTICAL ASTRO- 

 NOMY, the 5th Edition. Also, 

 The ELEMENTS of BOOK-KEEPING, the 7th Edition. 



