xlviii 



NATURE 



{June 5, 1879 



STANDARD AND OBSERVATORY TIMEKEEPERS. 



TRADEyf,r-„T\MARK MANUFACTURED BY E. DENT & CO. trade/^^^t^mark 



i]ENr 



mNT 



Guineas. 

 Standard Clock, suitable for Private Residences in Town 

 or Country, or Public Institutions, beating seconds and 

 going eight days with orce winding ; in cai-ved and 

 decorated oali or mahogany case ... ... from 35 



(a) The .same, but going one month with once 

 winding ... from 



Standard Observatory Mean-time Clock 



40 

 80 



(a) The same, but furnished with electrical contact 

 apparatus with eccentric screw adjustments for 

 dropping a time ball, or transmitting hourly 

 signals ... ... ... ... ... ... 92 



Standard Observatory Sidereal Clock 



(a) The same, but furnished with electrical contact 

 apparatus with fine vertical and horizontal screw 

 adjustments for transmitting seconds, currents 

 for controlling other clocks, &c. 



(b) 



The same, but arranged to omit the current at 

 every 6otii second, for pricliing on chronograph 

 barrel, &c. 



80 



95 



97 



(Guineas. 



Standard Observatory Clock, of the most refined con- 

 struction, with barometric compensation, &c. ... 160 

 (a) The same, with Sir Geo. Airy's e-capement ... 170 

 {b) The same, with M. Leverrier's electrical contact 



system 200 



The New Standard Clock [the primary standard tinukeeper of 

 the United Kingdom) of the Royal Observatory, Greenwich, wis 

 constructed by E. Dent &• Co., and precisely similar instruments 

 are now being made for the Royal Observatories of Spain and 

 Belgium. Standard Clocks of less refined construction for the Ob- 

 servatories of Edinburgh (Royal), Dimsink {Royal Irish), Oxford 

 (University), Pulkoxua (Russian Imperial), Geneva (National 

 Swiss); and many others, Foreign and Colonial, have been 

 manufactured. 



Galvanic Chronographic Apparatus, for registering 



the time of occurrence of transits and other astrono- 

 mical phenomena from 120 



The Great Galvanic Chronograph of the Royal Observatory, 

 Greenwich, and the still more pou'oful Apparatus for the Royal 

 Observatory, Brussels, and other smaller ones for other O'lserva- 

 lories were constructed by E. Dettt <£-= Co, 



E. DENT & CO., 



WATCH, CLOCK, AND CHEONOMETEE MAKERS, 

 61, STRAND, & 34, ROYAL EXCHANGE. FACTORY, GERARD STREET, LONDON. 



THE TELEPHONE COMPANY, LIMITED, 



36, COLEMAN STREET, LONDON, E.G. 



TESTIMONIALS. 



14S to 149, Tottenham Court Road, London, IV., 14M May, 1 8 79 

 2> ///^ Telephone Company, Limited, 36, Coleman Street, E.G. 



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

 venience, communicating 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 communication and recognition of the voice, must create a great demand for Telephones everywhere. — We remain, 

 dear Sirs, yours faithfuUy, (Signed) J. MAPLE & Co. 



Midland Railway Telegraph Department, Superintendent's Office, Derby, 2%th April, 1S79 

 Dear Sirs, — In reply to your inquiry of the 25th inst., I have the pleasm-e 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. 



MICROSCOPIC SPECIALITIES. 



Series I. — 24 Medical Pathological Preparations, 



in Case £z 2 o 



„ II. — 24 Physiological Preparations, in Case 220 

 ,, III. — 24 Educational ,, „ 220 



,, IV. — 48 Physiological ,, ,, 440 



Series V. — 24 Preparations from the Frog, in 



Case £z 



„ VI. — 24 Surgical Pathological Preparations 2 



A. — 48 Diatomaceas (selected) . 

 B. — 24 „ (very rare) 



2 

 2 



2 10 

 I II 



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



30A per doz. 



lis. to 



Descriptive Lists and full particulars on application to 



ARTHUR 0. COLE & SON, 



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

 Late of 62, St. Domingo Vale, Everton, Liverpool. 



Primed by R. Clay, Sons, and Taylor, at 7 and 8, Bread Street Hill, Queen Victoria Street, in the City of London, and publi^hei by 

 Macmillan and Co., at the Office, ag and 30, Bedford Street. Covent Gard«n.— Thursday. June 5. 1879. 



