\ Sept. 1 8, 1879] 



NATURE 



clxxi 



PROFESSOR HUGHES' AUDIOMETER. 



The only perfect measurer for testing the hearing power. Vide DR. Richardson's Report to the Royal Society, 

 May IS, 1879 ; Medical Times and Gazette, May 24, 1879. 



SOLE AUTHORISED MAKERS, 



KROHNE & SESEMANN, 



8, DUKE STREET, MANCHESTER SQUARE, LONDON, W. 



MICROSCOPIC SPECIALITIES. 



Series I. — 24 Medical Pathological Preparations, 



in Case £,z 2 o 



,, II. — 24 Physiological Preparations, in Case 2 2 

 ,, III. — 24 Educational „ ,, 220 



,, IV. — 48 Physiological ,, ,, 440 



Series V. — 24 Preparations from the Frog, in 



Case £2 2 o 



,, VI. — 24 Surgical Pathological Preparations 220 



,, A. — 48 Diatomacece (selected) 2 10 o 



,, B. — 24 ,, (very rare) I II 6 



IS^. to 



Pathological and Physiological Preparations in great and constantly increasing variety, and of most valuable descriptions. 



30i. per doz. 



Descriptive Lists and full particulars on application to 



ARTHUR C. COLE & SON", 



ST. DOMINGO HOUSE, OXFORD GARDENS, NOTTING HILL, LONDON, W. 



LATE OF 62, ST. DOMINGO VALE, EVERTON, LIVERPOOL. 



THE TELEPHONE COMPANY, LIMITED, 



36, 



COLEMAN STREET, LONDON, 



TESTIMONIALS. 



14S to 149, Tottenham Court Roac 



E.G. 



14S to 149, Tottenham Court Road, London, W., l/^h May, 1879 

 To the Telephone Company, Limited, 36, Coleman Street, E.C. 



Dear Sirs,— You will be pleased to hear that the forty Telephones you supplied answer admirably, and are of great con- 

 venience, coumiunicating as they do in some cases with our workshops a mile away. 



The simplicity and ease with which they work, being able to be used by any one, and the great advantage over the Telegraph 

 system in rapid couimanication and recognition of the voice, must create a great demand for Telephones everywhere. — We remain, 

 dear Sus, yours faithfully, {Signed) J. MAPLE & Co. 



Midland Railway Telegraph Department, Superintendent's Office, Derby, 28M April, 1879 



Dear Sirs, — In reply to your inquiry of the 2Sth inst., I have the pleasure to inform you that the Telephones which have 

 been erected on the Midland Railway are working very satisfactorily. — Yours faithfully, (Signed) W. LANGDON 



The Telephone Company, 36, Coleman Street, London, E. C. 



Application for Price Lists or further information to be made to the Manager. 



W. LADD 8c CO., 



SCIENTIFIC INSTRUMENT MANUFACTURERS 



{By Appointment to the Royal Institution of Great Britain), 



II AND 12, BEAK STREET, REGENT STREET, W. 



IMPROVED HOLTZ ELECTRICAL MACHINES, with 4 to 24 Plates. Immediately available in any condition of the atmosphere. 



LADO'S DYNAMO-MAGNETO MACHINE and GRAM.ME'S MAGNETO-ELECTRIC MACHINE for Laboratory use. 



Physical Apparatus of every Description. 

 ILLUSTRATED CATALOGUE, SIXPENCE. 



Mr. TENNANT, F.G.S., Professor of 



Mineralogy and Geology, Mineralogist by Appointment to Her Majesty 

 and the Baroness Burdett-Coutts, 149, Strand, London, W.C., Jiaving 

 been fifty years in busines.s, cunteinplates shortly RETIRING, and, 

 oll'crs for SALE several of his extensive COLLECTIONS of Minerals. 

 Rocks, and Fossils. They are well adapted for first-cla.ss Educational 

 Establishments, Provincial or Colonial Museums, or for the Private 

 Study of any Scientific Person wishing to become acquainted with the 

 above-mentioned Sciences, From ^1,000 to 5,000 Gumeas. Students' 

 Collections at 2, 5, 10, 20, to 50 Guineas. 



LECTURES on MINERALOGY applied 



to GEOLOGY and the ARTS, at King's College.— Prof. TENNANT, 

 F.G.S., will give Two Courses— (ne on WEDNESDAY and FRIDAY 

 mornings, from 9 to 10, and the nther on THURSDAY evening, from 8 

 to 9. The Public arc adinttted on paying the College Fees, \\z , .£3 3J , 

 for the Mr,rning Lectures arid^i iir. 6rf. for the Evening. The Lectures 

 begin WEDNESDAY, OC lOBER 8, and terminate atJhASTER. They 

 are illustrated by a large series of Specimens and Diagrams, chiefly frOTn 

 his Private Collection. Persons unable to attend Public Lectures can 

 have Private Instruction in Geology and Mineralogy of Prof. Tennant, 

 at his residence, 149, Strand. 



NOV/ READY, 

 SECOND EDITION, 



GRIFFIN'S 



CHEMICAL HANDICRAFT. 



PRICE Hi. 7<f. POST FREE. 



A CATALOGUE OF CHEMICAL APPARATUS; 



ILLUSTRATED, CLASSIFIED, DESCRIPTIVE. 



Demy Svo, 480 pp., Illustrated with 1,600 Woodcuts. 



Most Complete and Cheapest List of Apparatus, 



JOHN J. GRIFFIN and SONS, 22, GARRICK STREET,. 

 LONDON, W.C, 



