78 
(Mem. Lit. and Phil. Soc. VI. 617), consists of auroral obser- 
vations. Hence the first of Dalton’s apparatus which claims 
attention are the meteorological instruments. 
No. 1 is Dalton’s mountain barometer, with accompanying 
thermometer, made for him by the late Mr. Lawrence Buchan, 
a member of the Society. The barometer is enclosed in a 
wooden case which Dalton was accustomed to carry in his 
hand. 
Several home-made barometers used by Dalton in his 
observations are in possession of the Society. They are all 
of them filled, and the scales prepared, by Dalton himself, 
and are simple siphon tubes with a bulb blown on at the 
bottom to serve as a mercury reservoir. These are attached 
to plain pieces of deal upon the upper part of which the 
paper scale is pasted. One of these, which has probably 
also served for tension experiments (No. 2), has been placed 
in the collection. 
Many of the thermometers appear also to have been 
home-made. No. 3 is a mercurial thermometer evidentlv 
i/ 
made and graduated by Dr. Dalton, and marked with his 
initials, J. D. The freezing point of this thermometer was 
tested recently by Mr. Baxendell, who found that it had not 
altered since the instrument was graduated. Another 
(No. 4) is of the same kind and bears the date 1823; No. 5 
is a third mercurial thermometer with long stem and 
wooden scale ; No. 6 is an alcohol thermometer with wooden 
scale ; and No. 7 a registering maximum and minimum ther- 
mometer employed by Dalton, maker’s name J. Bonchetti, 
29, Balloon-street, Manchester. 
II. Apparatus Constructed and Used hy Dalton in his 
Researches. 
(1) “On the constitution of mixed gases,” (2) “On the 
force of steam or vapour from water or other liquids at 
different temperatures both in a Torricellian vacuum and 
