30 
head and the filmy nature of the tail. He also called attention, 
in another picture of this comet, not only to the main tail, 
but also to the beautiful splitting up of a very tenuous tail, — 
like the antennae of some insect. The comet of 1903, photo- 
graphed at Greenwich Observatory, showed six tails, disposed 
at all sorts of angles to the path of the comet, showing very 
well the phenomenon of the multiple tails of comets. An 
extraordinary comet without tail was discovered by Mr. 
Holmes, an amateur astronomer, in 1894. He was observing 
the nebulae in Andromeda, so that it was discovered by a 
lucky chance. Though a comet usually had a tail, it was clear 
that it was not a necessary appendage. 
Father Cortie dealt at length with Donati’s comet, discovered 
in 1858. The drawing showed that as the comet approached 
the sun the tail was turned away from the sun and became 
larger and larger the nearer it came to the sun. It was 
repelled by some repulsive force on getting near to the sun, 
and showed dark rifts of a hollow nature. The same appear- 
ance was manifested in one of De la Rue’s drawings. That 
comet was one of the most extraordinary seen in the last 
century. The orbits of three remarkable comets — those 
of Donati, Encke and Halley — were illustrated by slides. 
Halley was the first to see that comets followed the law of 
universal gravitation. One appearance of Halley’s comet 
was in 1456 and in that year according to Draper’s book on 
the opposition between religion and science, the Pope Alexander 
III ex-communicated a comet. He had enquired into that 
matter and found that the Pope said “ if the comet was as 
scientific men ascribed, a harbinger of woes, then we will 
order prayer to be said to avert the anger of God,” which was 
very different from saying the Pope ex-communicated it. 
This comet of Halley’s will return again in 1910, according 
to the researches of Mr Cowell and Mr. Crommelin. When 
Halley, who saw the comet in 1682, predicted that it would 
turn up again in 1758, he expressed a wish that, when it did 
turn up, posterity would credit an Englishman with having 
predicted its return. And it did turn up on Christmas Day, 
1758. It had already appeared 24 times in historical times 
and would reappear in 1910-13. There was a drawing by 
Herschel of its last appearance, representing it without and 
with a tail. The first comet ever photographed was by 
Sir David Gill, the Astronomer Royal at the Cape in 1882, — 
an extraordinary comet with a tremendous tail. It was so 
successful that it led to an international conference being 
called to consider the photographing of the heavens, and 
to-day eighteen observatories had almost identical telescopes 
erected to photograph the stars. 
