B1DWELL — HARBOUIl WORKS. 
255 
during my service there, and the third method was to he em- 
ployed for levelling the top of the mound of rubbio stone upon 
which the blocks would be founded when the rock was passed 
and a sand bottom reached ; this point had not been reached, 
however, at the time I left. Where the sand bottom occurs a 
foundation is made by depositing Rubble stone as mentioned. 
This is sometimes done from staging on to which wagons are run 
and their contents tipped into the sea, sometimes from Hopper- 
barges, and in some cases both methods are employed. The bags 
of concrete, the size of which varied from one ton to 20 tons, 
were deposited, the smaller from a special frame to which they 
were hooked and lowered down to the divers, who unhooked 
them when in place, and the larger from iron skips, of which the 
bottoms opened and allowed the bag to fall when over the spot 
in which it was desired to place it. 
When this foundation is levelled the blocks are placed upon 
it; at Peterhead this, aud the lowering of the bags, was done by 
a large horizontal-armed crane, known as a “ Titan, ’ with a 
power of dealing with loads of 50 tons at a radius of 100 feet, 
the largest blocks used there being of that weight. At the Tyne 
the blocks were set from staging until 1883, when a crane 
similar to that above, to set blocks of 46 tons weight at 92 feet 
radius, was erected on the North Pier and a similar one on the 
South Pier in tbo following year. Several other breakwaters 
have also been constructed from staging, among them those at 
Holyhead, Portland, Table Bay, &o. Staging has certain 
advantages, such as the fact that work can be carried on from it 
at more than one spot, lines and levels for the. " oi v can e 
ver y readily given and checked, work can ho carried on, so tar 
for instance as the depositing of a rubbio mound, in almost any 
weather. The heavy weight also of these large setting machines 
ls apt to cause unequal settlement of the new work as it act vances 
“Pon each succeeding length of it, unless the foundation is very 
sound, and I have seen a case where each successive length i ot 
»ew work was visibly broken off from the preceding K j 
after the crane had forked upon it for a time. f e '' er ^‘® J v . 
large machines have many advantages such as speedy 
handling, & c . Blocks are also sometimes set from bar 0 es, 
for this comparatively smooth water is of eourse ncccssaiy.^o^ 
they are more frequently used in river work i 
proper. 
The succeeding courses of blocks having been bro^o^ 
J? the required height the breakwater is usua y. ^ hjgh and 
the seaward side with a parapet, from intervals in this 
about the same thickness, and at regulai 
