40 
that light has been so long travelling through space before it reached this 
earth?* I have read the paper before us with great interest ; and, without 
committing myself to Mr. Pattison’s views on all matters, I may certainly 
say, I think that it is one of the most interesting and able papers that was 
ever brought before a scientific society. 
Mr. R. W. Dibdin. — I understand Mr. Charlesworth to say that we have 
reason for believing in the astronomical computation of time ; but we have 
no such reason for believing in geological computations. 
Mr. Charlesworth. — A geologist cannot give us the same test possibly. 
But his intellectual power and his scientific knowledge are the same. 
Rev. Dr. Butler. — How can we ascertain that the coral reefs have always 
gone on increasing at the same rate ? What data have we to show that 
thousands of years ago the coral reefs did increase at the same rate ? The 
argument is inconclusive as it stands. 
Mr. D. Howard. — There are one or two facts which I should like to bring 
before the meeting ; one is with regard to the question of the movement of 
gravel. The present rate of rivers never could have produced the results 
which have been attributed to it. It is a simple mechanical problem ; the 
power of water to move heavy bodies is a perfectly well-known quantity. 
It varies from nothing up to any force you will. Given, a certain current 
of water, running at a certain rate, at a certain inclination, it is not 
difficult to say what sized stone it will carry away. If it is not running 
with sufficient rapidity it will not move a single stone. A single hour of 
a sufficient current will move more gravel than centuries of a slower 
one. I remember, after a violent thunderstorm, passing through a valley 
of somewhat similar formation to that which has been referred to, and there 
was a sudden deposition of six or eight feet of gravel over the road. There 
we have a condition produced similar to that in the case mentioned, yet it 
does not mark a geological period at all. It would have taken a great many 
centuries to have produced that result by a gradual process. In measuring 
time in this way, we almost always discover that that very important factor, 
whether the process is constant, has been left out. As to the growth of 
stalagmite, it depends on the rapidity of the action upon calcareous rock> 
of carbonic acid in water. The stalagmite is no measure of time whatever ; 
the speed of its formation depends simply on the balances of power of 
solution and redeposition of calcareous matter in water charged with car- 
bonic acid, which is a chemical but not a chronological fact. One illustration 
shows how uncertain natural phenomena are in respect of time ; I allude 
to the extraordinary formation of vegetable growth in the Nile, which Sir 
* The nebula in Orion is said to be 60,000 years of light distant from 
us ; but certain considerations, not necessary to be referred to here, tend to 
make it a question whether the 60,000 should not be only 20 or 30 years 
(see also note on previous page). — Ed. 
