working at M. Tattegrain-Brule’s pit (and who had worked in the peat pit at 
other times) as to the depth, &c., of the peat, their account distinctly was 
that it did grow. He had not pressed the pomt at all ; the only questions 
he asked were as to the total depth, and as to what was at the base ot the 
neat The men agreed that it rested on the chalk, and was nowhere more 
than nine metres thick. M. Tattegrain-Brule corrected them so far as to say 
he knew of places where it was over 30 feet thick, and what was to the 
present purpose as regarded Sir Charles Lyell’s statement, they said that the 
peat was still growing or forming, and that about a metre in a century was 
the rate, according to their idea. His own conclusion in 1861 was that this 
was possibly an average estimate, because when they were altering the moat 
surrounding Abbeville he observed that there was a deposit of some two or 
three feet of peat in it, which they were clearing out, and he thought that 
they would at least have cleared their moat once in a century. I his was not 
far from the Porte Mercadet, a place often referred to m the account ot the 
dl He might mention the computation which was made for the growth of the 
peat in Ireland. This was, according to Mr. Griffiths, two inches in. depth m 
one near ; but this was an excessive growth,- and under peculiarly favourable 
circumstances. But before taking such data— the workmen s, which wild 
give at a metre one thousand years for the whole. 30 feet, and Mr. Griffiths 
computation, which would, under favourable circumstances (and m many 
places the Somme Valley presents these), leave it possible for the whole 
30 feet to have been deposited since the commencement ot t)ueen Anne s 
reign — he thought it well to call attention to an important consideration 
which affected materially any computation derived from peat-growth, 
namely, the intermittent character of the growth — its rapid growth at one 
time, its slow growth at another, and entire stoppage at others. When the 
peat, during growth, reached the highest level at which water would stand in 
any given locality, it naturally ceased to grow. From its character it could 
not raise itself to any great degree above the element on which it mainly 
depended for its growth. Of course, it might be in the varied incidents ot a 
long valley that the stream for some cause was kept back, but that could not 
be for long. The weight of the water would eventually break a course 
through the obstruction, and then the peat formed at the highest level would 
sink by reason of evaporation and its. own weight, and become more con- 
solidated, and form distinct beds of varied densities, such as existed m the 
peat, and which pointed to that intermittent character of growth. Con- 
sequently, until they knew what periods of rest took place, all computation 
was impossible, as the facts derived from the observation of incidental 
growth might have such a relation to the whole as to be not worth taking 
into account. , 
Mr. Parker’s view was, that only in a very few cases, was there any 
material growth of peat, such as when the water stood sufficiently above its 
surface as to supply the means of growth ; and that then it was very rapid, 
the conditions being as favourable as those in Ireland ; .and it followed, there- 
fore, that as the peat grew higher in the valley — higher, that is to say ,. m 
regard to the sea-level — so, fewer occasions would there be. of the water lying 
at a sufficiently high level to induce growth ; and from this, the probabilities 
were that in the earlier history of the peat, the occasions being more 
frequent, the beds would increase as a whole far more rapidly than they did 
He next turned to Sir Charles Lyell’s computation. This writer had 
selected the argument from M. Boucher de Perthes’ evidence, and though e 
said “we must hesitate before adopting it,” he gave it as the only one ox.any 
value, and did not intimate the least wherein any fallacy lay. It was given 
at p. 156. 
