304 
ON THE BREAKWATER AT MADRAS, 
opinions are grounded upon local knowledge 
and long experience of public works in India. 
This officer observes : 
“ A veiy small stone, laid on the mud or sand, at 
a depth of 70 feet water, will remain unmoved for 
ages. I should say that one granite, rough quarried 
of a cent weight would abide there, in the Madras 
road: as the work rises, it becomes more exposed 
to the action of the element; and, instead of a Oat 
yielding surface to stand and impress upon, it 
would have an inclined plane of hard substances 
like itself— but the weight of a stone increases in a 
triplicate ratio ; while its hoiizoniai section does 
ou\y duplicately ; the effect of the water may 
therefore be counteracted by increasing the size of 
the blocks. I again repeat what 1 have held, offi- 
cially and privately, that the base of the work should 
be left to Nature, and they will place themselves 
in their right situation ; and, above all, obseive to 
use the smaller stones first, reserving the larger 
blocks for the last ; you may safely employ stones 
under a ton weight down to half, or even a third of 
a ton, until your work is at man’s height from he. 
low the surface, or rather until you find that your 
apex is constantly thrown over, and blunted as it 
were you should begin your heavier stones, 
but cast them on the inner side; It would be idle 
to press your large blocks on the outer side. The 
well secured, the sea will never move the 
OMfer, after it has acquired the proper Talus. At 
this stage you will find the greatest difficulty, your 
work will often be disturbed ; not so much by the 
striking of the surf, as by the lifting of the waves ; 
the undulation of the water has that eft’ect; 
the waves subside with accelerating velocity, and 
rise with the velocity so accelerated, lifting or 
tending to lift the bodies it acts upon : hence it is 
that a work in the course of execution, suffers more 
when it reaches the trough of the waves, than 
when it is just at the surface. The first storm that 
occurred after my return from India, did some 
damage to the Plymouth Breakwater. I went to 
see it. 1 reported to the Admiralty, and stated that 
it was left too low, and that without a superstruc- 
ture it would greatly suffer. The following storm 
verified my predictions ; I saw very large blocks 
actually of their positions, where they 
could scarcely have been touched by the break- 
ers. Again 1 wrote to the Admiralty, for a stipe- 
structure which [ estimated at 60, 009 £, but 
Bennie, the Engineer, had sent in his estimate 
for £ 170 , 000 , to jface on both sides with large 
blocks, carefully fitted into each other, and I be. 
lieveclampt with iron. This mode has hitherto 
succeeded ; but even if it were the best, which f 
do not allow, at so great a cost, he has an advantage 
fAere which you have not on your coast; a great 
rise fall of water in spring tides, when the 
lower tiers could easily be ranged in their places. 
With you, 1 think a superstructure is indispensable, 
to rise 12 or 15 feet above the surface of the sea, for 
you must not flatter yourself that yonr wotk, ter- 
minated m a/rex, some few feet above the sur- 
face, will hold. When brought to that state, it 
should remain till storms and swells have settled it, 
so as to form a surface sufficiently wide for a super- 
structure. This may not be for a year or two, or 
more ; during which you will watch the operation 
of the waves upon it, and take your measures for 
its completion, and extension. What 1 mean for 
the figure of the work aud my distinction of large 
There will be great saving of mateiials by this 
mode of erection, for I am certain the idea of the 
work assuming a wide base at a great depth of water 
is quite erroneous ; and whatever more is given to 
it than the weight and shape of the stones would 
effect, is ivaste to all intents and purposes. Your 
superstructure should be 13 or 15 feet thick; and 
probalrly nearly as high. 
There is a- great advantage in this way of pro- 
ceeding; that, however, the work may suffer from 
time to time, it can only become more consistent 
and secure; it must, in the end, bring the wor k, if 
persevered in, to its intended use and effect. Yon 
should make some allowance for subsequent opera- 
tion?, when you determine on your distance from 
the shore ; all that is thrown over, will fall within 
the work. I think 20 feet a good depth for the 
object now in view, measured from the clayey 
bottom ; whatever there may be of sand above it 
will move away when the work is completed. 20o 
yards in length is little enough— but the horns of 
your work will give it length. That dimension 
however is of the least importance, as it may sub- 
sequently be added to, when its operation has been 
observed ; and thence you may best know at which 
end to make the addition. The angle at the shoulder 
of your horns, which will act as the starlings of 
abridge, should form an angle of about 150 deg. with 
the line of the breakwater ; when the body of the 
work is raised, the lengthening of the horns will 
accelerate the cuirent, and keep clear of sand the 
space in shore. I observe" you expect an accumula- 
tion to foim opposite the centre of the breakwater, 
in a curved line against the bulwark: upon this 
point I differ from you ; I think, on the contrary, 
that your horns will make the water deepest there, 
and accumulate the - sand on the opposite side 
against the Breakwater. tV hen the work is com- 
pleted, it will be convenient in every respect to erect 
a quay with cranes, on the line drawn on your plan, 
where you expect the accumulation ; and ultimately 
a similar quay where I expect it to be formed; 
whereby the current will be greatly accelerated . 
The horns may, by degrees, be lengthened, if re- 
quired, to clear the passage of sand; hut it is 
probable that during the cAflTige of the monsoons 
some little deposit may form at each end of the 
passage, till the set in cuirent again removes it.— 
I perceive you propose taking the stones from the 
■Adiar bank in catamaiaris over the bar.— I have my 
doubts if that is the best way ; however, I see you 
have tried it with some success, and, during the 
south west monsoon, you may not find it so labori- 
ous. In the north east season, except you have a 
steamer, I fear you will not progress much.— rtf- 
ter the breakwater is raised so as 10 affect the surf, 
you may perhaps do better, by bringins: the stones 
from the Mount down to the Custom House; this 
would he for \\\e large stones especially. 
Should this undertaking answer your expectations, 
I should in your place keep in mind the construction 
of a railway, from the south side of the Adiar. — 
It has long been in my contemplation,— Nay, 1 be- 
lieve, in some of my reports, I hinted at one, or a 
carrying Nullah from the Seven Pagodas at 
Mahabalipooram, to biing the fine granite in that 
neighbouihood to Madras, 
If your horns are extensive, the intermediate space 
outside will fill up to a certain degree with sand,, 
during what I may call the aquastice season, or 
during a succession of mild luonsoons ;— and in 
time a counter breakwater may be made beyond 
this accumulation, so as to form a solid body in this 
shape,'* 
