clvi 



NATURE 



[Sept. 4, 1879 



STANDARD AND OBSERVATORY TIMEKEEPERS. 



^f^'^^^iyj^ARK MANUFATURED BY E. DENT & GO. •^«^°^''^^|^^ 



Guineas. 

 Standard Clock, suitable for Private Residences in Town 

 or Country, or Public Institutions, beating seconds and 

 going eight days with orce winding ; in carved and 



decorated oak or mahogany case from 35 



(fl) The same, but going one mouth with once 

 winding from 



Standard Observatory Mean-time Clock 



(a) The same, but fm-nished with electrical contact 

 apparatus with eccentric screw adjustments for 

 dropping a time ball, or transmitting hourly 

 signals 



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 60th second, for pricking on chronograph 

 barrel, &c. 



40 

 80 



92 

 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 escapement ... 170 



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



system 200 



The New Standard Clock (the primary standard timekeeper of 

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

 constructed by K. 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), Dunsink (Royal Irish), Oxford 

 (University), Pulkowa (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 poii'crful Apparatus for the Royal 

 Observatory, Brussels, and other smaller ones for other Observa- 

 tories were constructed by E. Dent d-» Co, 



E. DENT & CO., 

 WATCH, cloce:, and cheonometer makbbs, 



61, STRAND, & 34, ROYAL EXCHANGE. FACTORY, GERARD 8TREET,a0ND0N. 



MICROSCOPIC SPECIALITIES. 



Series I. — 24 Medical Pathological Preparations, 



in Case £2 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 £2 2 o 



,, VI. — 24 Surgical Pathological Preparations 2 2 



,, A. — ^48 Diatomaceas (selected) 2 10 o 



,, B. — 24 ,, (very rare) I II 6 



Pathological and Physiological Preparations in great and constantly increasing variety, and of most valuable descriptions. 15J. to 



30/. per doz. 



Descriptive Lists and full particulars on application to 



ARTHUB C. COLE & SON, 

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



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



CHEMICAL APPARATUS-SCIENTIFIC INSTRUMENTS. 



Apparatus for the Analysis of Water according to Professors Frankland and Bischof. 



BUNSEN'S MODIFIED FILTER PUMPS, from 10s. 8d. to 67s. 



ELECTRIC LAMPS FROM 35s. UPWARDS, AND BATTERY OF 40 QUART BUNSEN'S CELLS FOR SAME AT £8. 



GEISSLER'S TUBES. 



Catalogues and Illustrations will be sent gratuitously. 



A Liberal Discount allowed to Wholesale Buyers. 



WHOLESALE IMPORTERS and MANUFACTURERS, 



AUG. BEL and CO., 



Sole Agents for Grenefs Bmtteries, and Contractors to the Govommeni. 



34, Maiden Lane, Southampton St., Strand, W.O. 



Sets of Apparatus as 

 required by the Govern- 

 ment Sch:)ols always 

 ready and kept in stock. 



CAILLETET'Q APPARATUS FOR L ISSUER ACT ION OF GASES- 



For the convenience of Teachers and Students at the South Kensington Classes, the Science and Art Department has authorized us to keep a stock in 

 the store-room, first floor of the building, where the dififerent sets and other articles are always ready for delivery. 



Printed by R. Clay, Sons, and Taylor, at 7 and 8, Bread Street Hill. Queen Victoria Street, in the City of I>ondon, and publiihed by 

 Macmillan and Co., at the Office, 29 and 30, Bedford Street, Covent Garden.— Thursday. September 4, 1S7Q. 



