RAIRD &TATLOCK (LONDON) LTD. 



New Pattern Standard Hygrometer for use in 



Cotton Factories, 8?c. 



(Registered No. 606642.) 



4149-4150 



This New Pattern Hygrometer has been devised by us to comply with the Home Office 

 Regulations for use in cotton factories, and is the pattern adopted by the Blackburn and District 

 Cotton Employers' Association and made by us to their order. 



The scales are of strong porcelain with figures and divisions burnt in and are extremely 

 legible at a distance. They also have the advantage of being always easily cleaned. The 

 thermometer bulbs are of Jena normal glass and tubes are accurately divided in J F. 



The oak frames are designed so that the thermometers can be readily taken out at any time, and are made 

 with strips of wood at back to keep the frame away from the wall. They comply in every respect with the Home 

 Office Regulations. Between the two thermometers, an enamelled zinc plate is fixed with the table of humidity 

 and a copy of the Regulations as to artificial humidity, as provided by the Home Office Regulations of 21-12-11 

 printed thereon. 



The brass wire guard is strongly made and is hinged at top so that easy access can be had to the wet bulb 

 for the weekly changing of the muslin wick. 



4149 Hygrometer complete as figured, with National Physical Laboratory Certificate for 

 each thermometer 



1 1 



4150 Spare Thermometers, with N.P.L. Certificates 



per pair 16 6 



CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS- 



