Farrctover.—On the Constitution of Comets. ATT 
to be the result of mere accident. Sometimes unimportant circumstances 
—such as the position of the door or fireplace, or the best place for the 
blackboard—have decided the matter. More frequently it has depended on 
the desire to have the faces of the children in full light. Against this I 
have already declared myself. Most frequently, however, the wish to place 
the children as near as possible to the master has regulated the arrange- 
ment, and has led to placing the seats in a horseshoe form ; but also in 
this arrangement only one-third of the children can have a proper light. I 
admit it is very difficult to answer all requirements in this respect, especially 
if the schools have not been built with a proper consideration to the 
hygienies of the human vision. However, in most class-rooms it would be 
easy to make the necessary alteration—to have the light come from the 
left-hand side, and, by raising the benches one above the other, or, simpler 
still, by sufficiently raising the master’s place, to enable the teacher to sur- 
vey the whole class at a glance. 
I am afraid my advice in this matter will not soon be practically 
followed, as even in Europe only after years of urging and preaching have 
the necessary alterations been made in schools ; but my paper has at least 
drawn attention to the matter, and it must rest in the future what fruit 
it will bear. 
Arr LX.—On the Constitution of Comets. By the Rev. P. W. FargcrLovon. 
[Read before the Southland Institute, 10th October, 1882.) 
Kerer, with the prescience of genius, supposed that comets throng in 
space as fish in the sea. It is true that only some 650 comets are recorded 
as seen during the Christian era, and that a considerable number of these 
have been reappearances of periodic visitors. But of these 650, about 120 
have been seen in the Nineteenth Century,—mostly telescopic, however. 
This large number is owing to improved methods of observing. As many 
as eight have been seen in one year, and we have in our morning sky the 
fourth for the year 1882. Now, it is certain that not half the comets that 
approach the sun, within the range of the telescope, are seen by man. It 
may also be regarded as highly probable that vast numbers of comets have 
their perihelia at distances which preclude their discovery. 
A comet crossing the solar frontier with the momentum of a few miles 
per annum, along a line forming an angle of 45° with the radius from the 
sun’s centre to the comet's centre, at the moment of crossing, would secure 
a perihelion distance of many millions of miles. If, however, the momen- 
tum amounted to miles per hour, the comet would be carried far too wide 
of the sun to be observed by the inhabitants of the earth, 
