SALMON AND TROUT CULTURE. 465 
A grating fine enough to keep the young fish within bounds 
chokes up with rubbish in a few minutes, and is carried away 
bodily or the water is forced into another channel ; in either 
case the fish are liable to pass out of bounds, and they are 
virtually lost to the original owner. The safest plan to adopt 
in the construction of ponds is to excavate rather than to dam 
up ; it is very much more expensive, costing as a rule between 
eight- pence and a shilling per cubic yard ; but this is much more 
than balanced by the security against unsound heads of dammed- 
up ponds. If the soil is suitable, however, a thoroughly sound 
‘head’ is easily made, the thickness of which must depend‘on 
the weight of water behind it ; but the head should in no case. 
be less than eight or ten feet through, and it is sometimes 
necessary to make it as thick as thirty feet. The inside of 
pond-heads should shelve off towards the centre of the pond at 
a considerable angle, but as much depends on local circum. 
stances, no hard and fast rule can be laid down. Camp- 
sheathing, or planking, is necessary in some places, and brick 
heads may have to be formed where space is limited, and where 
a perpendicular head is required. If ponds are well made in the 
first instance, there need be no danger of the head breaking away. 
In making ponds, it is most desirable to have the ‘outlets’ 
very capacious, so as to take off any extra water in a very wet 
season. Ponds for business purposes should also be constructed 
within easy distance of a railway station, and where good fresh 
water can be obtained on the road and added at the last 
moment. The cost and risk of removing yearling and older 
fish are very much lessened in such a case. er contra, very 
many fish are killed by the addition of unsuitable water on the 
journey, and except in well known localities, I never allow 
water to be added after the consignment has been sent off, pre- 
ferring to send fewer fish in one vessel, or, which amounts to 
the same thing, a sufficient quantity of water to last out, and 
keep the fish alive; it is the rarest thing for any of my fish 
to be lost on the road. 
A fish-breeder, who looks for some return for the money 
laid out on his ‘fishery,’ must be able to put his hand on any 
L HH 
