-110 WATER SUPPLY IN THE INTERIOR OF NEW SOUTH WALES. 
tank which has been silted up is a work of very a difficulty, for 
long after the water has dried out the extremely fine mud remains 
in a semi-fluid state, incapable of being shovelled, tr even after 
the surface has become dry the mud underneath is so soft that it 
cheap to excavate a new tank as to clean out an old one which has 
been silted up. Another source of difficulty would be the necessity 
for allowing the tank to dry out, which could not be done if the 
country were fully stocked, without first providing some other way 
of watering or removing t 
Thinking over this nist Ries seeing its importance in the 
future as the country is becoming overspread with excavated 
tanks, which ontly't in a few cases have yet had time to silt up, it 
has seemed to me that it might be possible to clear out the silt 
and even materially to deepen and enlarge the tanks while they 
were full of water; and if beh te ee in other places is 
borne out in this instance, it might even be done more cheaply 
than excavating in the first place. “In ‘he ‘ips that some one will 
test it practically, I will make the suggestion. The method I 
would suggest is to excavate the silt while the tank is full of 
water in a wet season. Silt is removed from a depth of 20 feet 
of water in harbours sont carried out to sea at a cost, i believe, of 
could be dredged out for about one-third the cost of removing the 
dry earth. On the Panama Canal dredging machines are now 
being used, by which the silt is raised in the usual way by means 
of buckets on an endless chain and then passed into pipes through 
which it is dumped at some distance from the bank. 
Knowing these things, it seems that it should be possible to con- 
struct a smal dredging machine, in parts, so as to be portable, put 
it together on the station or on the ta nk, and then dredge out the 
certain—these tanks must be made very much larger in the future 
_ than they have been in the past, and some means must be found to 
make them more permament. I offer this —- as a possible 
way of attaining these ends. 
