326 
PEOFESSOE W. THOMSOX AXD DE. J. P. JOULE OX THE 
Seeies I. — Bulb ‘26 inch diameter. 
Velocities in the 
alternate experiments, 
in feet per second. 
Difference of 
thermal effect. 
Estimated effect 
of low velocity. 
Thermal effect 
of high velocity. 
Telocirv due 
to 1- C. 
46-9 and 24 
6*082 
6*018 
O 
0*1 
148*8 
51*5 and 24 
0*098 
0*018 
0*116 
151*2 
68*1 and 24 
0*]51 
0*018 
0*169 
165*6 
72*7 and 24 
0*191 
0*018 
0*209 
159 
78*7 and 24 
0*228 
0*018 
0*246 
158*6 
84*8 and 24 
0*251 
0*018 
0*269 
163*5 
103*7 and 24 
0*333 
0*018 
0*351 
175 
130*2 and 24 
0*531 
0*018 
0*549 
175*7 
133*2 and 24 
0*607 
0*018 
0*625 
168*5 
145*4 and 24 
0*676 
0*018 
0*694 
174*6 
Seeies II. — Bulb -48 inch diameter. 
A'^elocities in the 
alternate experiments, 
j . in feet per second. 
Difference of 
thermal effect. 
Estimated effect 
of low velocity. 
Thermal effect 
of high velocity. 
Velocitv due 
to 1° C. 
1 36*3 and 18 
6*039 
6*015 
6*054 
156*2 
i 66*6 and 1 8 
0*112 
0*015 
0*127 
186*9 
84*8 and 18 
0*158 
0*015 
0*173 
203*9 
125*6 and 18 
0*427 
0*015 
0*442 
189 
In the following experiments, made in the spring of 1859, thermo-electric junctions 
of copper and iron wire were whirled, and the effect measm-ed by a Thomson’s reflecting 
galvanometer. The arrangement will be understood from the adjoining sketch, where 
a is the axle of the whirling appa- 
ratus. h a block of wood placed on 
the end of the axle ; to this is at- 
tached c d, a copper tube, -j^-ths of an 
inch in diameter, with a hole in its 
side. e is a copper wire, which, 
entering the hole passes along the 
axis of the tube, from which it is in- 
sulated by non-conducting material. 
(If is an iron wire soldered at cl to 
the copper wire, g g are thick cop- 
per wires, communicating at their 
remote ends with the galvanometer. 
They apply to the tube and wire Avith 
a springing force, perfect contact 
being maintained by keeping the touching surfaces clean, and lubricated with oil. A 
thin piece of wood, not draAvn in the sketch, was attached to the block of wood. It 
was made to extend to within 1, 2, or 3 feet off d, according as the velocity was to be 
