OF METEOROLOGICAL INSTRUMENTS. 



FIG. 40. 



FIG. 43. 



The Value of this Instrument is shown by the following Testimonials : From SIR HENRY 

 JAMES, E.E., F.R.S., Director of the Ordnance Survey and Topographical Dep6t of the War 

 Department, Author of ' Instructions for Taking Meteorological Observations,' with Tables, 

 Notes, &c. : 



" I have great pleasure in stating that, after having had one of your Mercurial Minimum Thermometers 

 carefully observed and registered at this office, and one at Southampton, during a period in which we have 

 had a great range of temperature, I have found it to act perfectly, and never once to get out of order. I 

 therefore think you have achieved a great success, and hope you will receive its reward. " 



B. STEWART, LL.D., F.R.S., Director of the Kew Observatory, in his Description of the 

 instrument before the meeting of the British Association for 1862, said : 



" Before bringing this instrument to the notice of this association I have carefully tested its action at the 

 Observatory, and find its indications in every way satisfactory." 



From T. LAWRENCE, ESQ., Medical Staff, Mooltan, Punjaub : 



" Your Mercurial Minimum Thermometer works admirably. It seems to me the only instrument adapted 

 for minimum registration in this climate." 



39. Minimum Thermometer, filled with pure alcohol, for ordinary registration, 



engine divided on the stem, and mounted to correspond with the Standard 

 Maximum, No. 28 (fig. 39, p. 10) . . . . 100 



40. MINIMUM THEEMOMETEB, for terrestrial radiation, divided and figured on the 



stem, which is enclosed in a glass cylinder for protection (fig. 40) 100 



42. MINIMUM THEEMOMETEB, on brass pedestal stand (fig. 42, p. 13) 140 



43. Casella's Extra Sensitive Minimum Thermometer for terrestrial radiation. 



- The unavoidably high price of CASELLA'S Mercurial Minimum Thermometer, 

 as well as the care required in using it, has induced him to design the one 

 shown in fig. 43, in which the bulb, being extended in the forked form 

 therein shown, exposes a much increased surface to the air, and thus renders 

 it little, if anything, less sensitive than the mercurial thermometer. It is 

 really interesting to note the increased sensitiveness of this over standard 

 instruments of the usual form . , . . .150 



14. CASELLA'S EXTEA SENSITIVE MINIMUM THEEMOMETEE, forked as fig. 43, on 

 porcelain scale, with hardwood back to correspond with standard maximum, 

 No. 28 . 150 



