TO CORRESPONDENTS. 



Mr. BoAz's Paper on an Universal and Invariable Standai'd of Measure has 

 not been forgotten. 



Mr. Dobbie's Communication on the Magnetic Power of the Poles of the Earth 

 has been received. 



Our Correspondent X. is referred to our last volume, page 6. But without 

 seeing that which he inquires about, we cannot answer with certainty. 



Our Meteorological Table will be still further improved next month, as our re- 

 spected Correspondents have kindly arranged to make their daily observations 

 at Gosport and Boston at the same hour. 



On the First of June will be published, in 2 vols. 8vo, with 17 plates, 

 price 21 5. 



THE HISTORY and DESCRIPTION of the MUSEUM of NA- 

 TURAL HISTORY, and ROYAL BOTANIC 'GARDEN, at 

 PARIS, being a full Account of the Enlargement and]| Progress of the 

 several Collections this magnificent Establishment contains in Zoology, 

 Mineralogy, and Botany ; composed by authority of the French Govern- 

 ment, from the Notes furnished by the Professors and Administrators of 

 the Museum. 



Translated from the French of M, Deleuze, Assistant Botanist, by 

 A. A. RoYER, Illustrated by three Plans of the Establishment at three 

 different periods, the last being a most accurate delineation of its present 

 distribution : also with l^ superb Engravings, being Views of the most 

 conspicuous parts of the Galleries, Gardens and Menagerie, by the first 

 Artists. To which is added, 



An Appendix, containing the names and particular functions of the 

 persons now at the head of the Institution, the services rendered by thera 

 to Science, and the works they have published. Also, the particular days 

 and hours when Foreigners and Students are admitted in the Galleries, 

 Menagerie and Gardens ; directions how they are to proceed, in order to 

 become acquainted thoroughly with the Establishment without loss of 

 time : and lastly, a concise explanation of the mode adopted in the Labo- 

 ratories of the Museum, for collecting, preserving and stuffing the skins 

 and remains of animals, &c. 



Sold for the Proprietor, A. A. Royer, by G. B, Sowerby, 33, King- 

 street, Covent-garden. 



N.B. The first Volume is now ready for delivery. 



This Day are published, Numbers I. to XIV. of the •' 



GENERA of RECENT and FOSSIL SHELLS, for the us? of Stu- 

 dents in CONCHOLOGY and GEOLOGY; to be continued ia 

 Monthly Numbers, each containing Six Plates of Genera, with corre- 

 sponding Letter-press, descriptive of the Characters by which each Genus 

 is distinguished; the Land, Fresh-water, and Marine Nature of each Ge- 

 nus will be particularly noticed, as well as the Strata in which the Fossil 

 Species occur. 



It is the intention of the Authors to select the most characteristic spe- 

 cimens in illustration of the Genera, and the Plates will be all original and 

 executed in a superior manner. The descriptive part and observations 

 will be conducted by George Bhettingham Sowerby, F.L.S., who 

 feels confident that he will be able, assisted by the excellent Engravings 

 with which it will be illustrated, to render this Work in every respect 

 highly deserving of the public patronage he earnestly solicits for it. All 

 unnece5sary multiplication of the Genera will be avoided, and the Work 

 will be concluded in as few Numbers as possible. A Classification of the 

 Plates will be given at the conclusion. The price of each Number will 

 be 4fS. plain, and 6s. highly finished in colours. 



Published by G. B. Sowerby, 33, King-street, Covent-garden ; and may 

 be had of Messrs. Sowerby, 2, Mead-place, Lambeth ; Sherwood and 

 Jones, Paternoster-row ; Hatchard and Son, Piccadilly ; Phillips, George- 

 yard, Lombard-street; Hearne, 81, Strand; Stutchbury, 3, Dove-court, 

 Old Jewr y ; and J. Pichard, Quai Voltaire, Paris, where Copies are depo. 



