cliv 



NATURE 



[Sept. 4, 1879 



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. 



EAGLE INSURANCE COMPANY, 



79, PALL MALL. 

 For Lives only. Established 1807. 

 Net Premiums and Interest .»»..«»....». ;^396,8i8 

 Accumulated Funds ...»..«».».»..»». ;£3,o83,28i 



Also a Subscribed Capital of more than ... .» >^i, 500,000 



Reports, Prospectuses, and Forms may be had at the Office, or from any 

 tA. tlie Company s Agents, post free. 



GEORGE HUMPHREYS, Actuary and Secretary. 



NO\A^ READY, 

 SECOND EDITION, 



GRIFFIN'S 



CHEMICAL HANDICRAFT. 



PRICE ^s. yd. POST FREE. 



A CATALOGUE OF CHEMICAL APPARATUS; 



ILLUSTRATED, CLASSIFIED, DESCRIPTIVE. 



Demy 8vo, 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. 



S. 0. TISLEY & Co. 



OPTICIANS, ■* 



172, BROMPTON ROAD, S.W. 



(Close to South Kensington Museum). 



THE PHONEIDOSCOPE 



An Instrument for Observing the Colour-Figures of Liquid Films under the 

 action o£ Sonorous Vibrations. 



■Being a visible demonstration of the Vibratory and Molecular Motion of a 

 Telephone Plate. 

 The PHONEIDOSCOPE, with 3 Discs, Bottle of Solution, Descriptive 

 Pamphlet, &c., in Cardboard Box, xos. 6d. 



MANUFACTURED AND SOLD WHOLESALE AND RETAIL BY 



S. C. TISLEY & CO., 172, BROMPTON ROAD, LONDON, S.W. 



■TELEPHONIC ELECTRICITY. All Materials suppUed for experi- 

 mental purposes. 



Price Lists cf Electrical and Acoustic Apparatus, with Drawings and 

 Description of the Hannonos^raph, Post Free, Q.d. 



W. F. STANLEY, 



Mathematical Instrument Manufacturer 



To H.M.'s Government, Council of India, Science and Art 

 Department, Admiralty, &c. 



"Mathematical, Drawing, and Surveying Instruments of every description, o£ 

 the highest quality and finish, at the most moderate prices. 



Price List post free. Engine Divider to the Trade, 



ADDRESS-- 



GREAT TURNSTILE, HOLBORN, LONDON, W.C, 





HOLLOWAYS PILLS 



THIS 

 MEDICINE 



1« a Certain Cure for «U Disorders of the LIVER, STOMACH 

 AITD BOWELS. A Great FTTBIFIEK of the BLOOD; a 

 Powerful Inyigorator of the System, in cases of WEAKNESS 

 AND SEBU.IIT, and is nneiittaUed in Female Complaist» 



BARCLAY & SON, 



138, REGENT STREET, LONDON. 

 To Her Majesty and H.R.H. the Prince of Wales. 



DUPLEX LAMPS. 

 MODERATOR LAMPS. 



READING LAMPS. 



MICROSCOPE LAMPS. 



BEST COLZA OIL. 



A I KEROSINE OIL. 



WAX, SPERM, 



AND 



PARAFFINE CANDLES. 



ILLUSTRATED CATALOGUES POST FREE." 



Now ready, a Revised Edition. 



NEGRETTI & ZAMBRA'S 



encyclop.s;dic 



Illustrated, and Descriptive 



CATALOGUE OF 



SCIENTIFIC INSTRUMENTS. 



(Containing very numerous Comparative Tables of Reference and 



Illustrated by upwards of TWELVE HUNDRED ENGRAVINGS. 



Six Hundred Pages, Royal 8vo, cloth, gilt lettered. Price sj. 6d.) 



Ojtical, Mathematical, Philosophical, Photographic, 



AND 



STANDARD METEOROLOGICAL 



INSTRUMENTS. 



MANUFACTURED AND SOLD BY 



NEGRETTI AND ZAMBRA, 



Opticians and Scientific Instrument Makers to 



The Royal Observatory, Greenwich ; theAdmlralty; Hon. Board of Ordnance: 



Board of Trade ; the British Meteorological Sjcifity; the Observatones 



Kew, Toronto, Washington, Victoria ; East Indian Government. 



HOLBORN VIADUCT, E.G. 



ALSO AT 



45, CORNHILL, E.G., & 122, REGENT STREET, W., 

 LONDON. 



