294 Proceedings of the Royal Society 
I. 
II. 
III. 
IV. 
V. 
VI. 
Ee-Zn . . 
23°*8 C. 
99° C. 
1-43 
1-404 
198° C. 
Pe-Zn . . 
28°-25 
94° 
1-373 
1-3397 
198° 
Fe-Zn . . 
24°*5 
94° 
1-429 
1-353 
198° 
Pb-Zn . . 
17° 
96°-8 
-416 
•4275 
- 79° 
Pb-Zn . . 
o 
00 
r— 1 
96°-5 
-488 
•434 
- 79° 
Zn-Arg . . 
18° 
98°-5 
-730 
-638 
-330° 
Zn-Arg . . 
18°-5 
86°-5 
-718 
• -678 
- 330° 
Pb-Arg . 
18°*6 
95° -5 
-682 
r(-636) 
\_Note , — Mr Camplbell sent me portions of his iron and German- 
silver wires to test. The electromotive force of a circuit of these 
wires was found to he almost exactly proportional to the difference of 
temperatures of the junctions between 10° C. and 100° C. — P.G.T.] 
2. On the Problem of the Lathe-Band, and on Problems 
therewith connected. By Edward Sang. 
That of the lathe-band is one of those simple-looking problems in 
elementary mechanics- which present serious difficulties to the 
investigator. The problem is this — “ So to arrange the several 
diameters on the fly-wheel and pulley-cone of the turning-lathe, as 
that the Same band may suit for all.” The solution consists of two 
steps converse to each other, the one being “ to compute the length 
of the band from given diameters,” the other “ to compute new 
diameters which may suit the length so found.” 
If A represent the lathe centre, B the centre of the fly-wheel, 
and if a circle be described round B, having its diameter KBH equal 
to the difference between the diameters of the wheel and pulley, the 
two tangents GA, Ag, together with the arc gHG, give the excess 
of the length of the band over the circumference of the pulley, while 
the same two tangents exceed the arc GKg by as much as the band 
