1919 .] 
Astronomical Notes. 
197 
The calculations may be arranged conveniently in tabular form as under, 
and are readily carried out by means of a calculating-machine. 
u. 
nt. 
t. 
V. 
V. 
Days. 
1 = Distance 
o 
o 
Sun-Earth. 
o 
1 
0-032769 
2-53 
0-5898 
7-75 
2 
0-065831 
5-08 
0-5978 
15-42 
3 
0-099481 
7-67 
06110 
22-96 
4 
0-13402 
10-34 
0 6296 
30-30 
5 
0-16974 
13-09 
0 6533 
37-41 
6 
0-20692 
15-96 
0-6823 
44-23 
7 
0-24587 
18-97 
0-7165 
50-74 
8 
0-28687 
22-13 
0-7561 
56-94 
9 
0-33023 
25-47 
0-8009 
62-79 
10 
0-37623 
29-02 
0-8509 
68-31 
11 
0-42516 
32-80 
0-9061 
73-49 
Thus t, r, and v are easily obtained, and the positions of the comet can be 
plotted in the plane of the orbit. 
If a model is made with the line of nodes as a hinge, and with the 
plane of the orbit inclined at the angle i to the plane of the ecliptic, it will 
be seen how the polar co-ordinates may be converted into rectangular 
co-ordinates referred to the ecliptic ; and if the model also shows the 
plane of the equator the transformation of the co-ordinates into equatorial 
co-ordinates can be made. C. E. A. 
HEATING HOUSES BY ELECTRICITY. 
An instructive report on the heating of houses was published recently 
(28th February, 1918) by the Hydro-electric Power Commission of Ontario, 
in which the cost of electrical heating is compared with that of heating 
with coal. 
This is an important document, being an official statement by a large 
hydro-electric power concern. It applies, of course, to Canadian con¬ 
ditions, the fuel consumption in the average eight-roomed house being 
taken at 9 tons of anthracite per year, valued at £2 10s. per ton—Ac., 
£22 10s. per year. To do the same heating by electric power would require 
a maximum demand of 16 horse-power, and would cost over £70 per year. 
Moreover, if general, it would require over a million horse-power for the 
city of Toronto alone. Undoubtedly electric heating, apart from its cost, 
approaches more nearly the ideal than any other fo m of heating, but the 
object of the report is to eradicate from the popular mind the idea that 
electricity is destined under Canadian conditions to take the place of coal 
and other fuel for the heating of houses. 
Applied to New Zealand conditions the same conclusion is generally 
correct, although owing to the milder weather conditions the discrepancy 
is not so great. The ordinary open fire will consume £3 to £4 worth of 
coal or wood per year. A radiator on for 1,200 to 1,500 hours per year 
will cost £6 to £10 per year, and, though it gives a steadier heat throughout 
the day, it will not give the same maximum output of heat as the coal or 
wood fire. . L. B. 
