E. Dozson.—State of Applied Science in Canterbury. 141 
amount of such error, and this can readily be done. The permanent mark 
on the central tower consists of a batten six inches wide, with a black stripe 
one inch wide down its centre. The eye-piece of the transit instrument, 
being furnished with five vertical wires, placed at equal distances apart, 
the value of the space between any two wires, at a distance equal to that 
of the mark on the tower, can be ascertained by reference to the width 
of the batten, which thus gives a scale by which the error in the position 
of a light, placed in the tunnel under the tower, can be rated with great 
exactness. 
Although it is not probable that any important extension of our railway 
system can be undertaken at present, it is satisfactory to know that the 
surveys of the Southern Railway have been carried down to the Waitaki, 
and connected with those made by the Railway Engineer of the Otago 
Province, and that the necessary reserves have been made so far as the lines 
run through land belonging to the Government. 
Rrvers.—During the last few years great changes have taken place ir in 
the channels of some of our large rivers, both on the East and West Coasts. 
The Rangitata has for some years past been scouring out for itself a new 
channel down what is known as the Deep Creek, the original main river-bed 
being now almost deserted by the water. It is worth putting on ‘record 
that this great change, which seriously affects a large extent of pastoral 
country, had its origin in the cutting of a ditch to form a sheep boundary, and 
the run of water thus established has gradually attained such dimensions as 
to cause the diversion of the greater part of the river from its original bed. 
The Waimakariri, which used to deliver the great bulk of its waters through 
the channel on the south side of the Kaiapoi Island, has shifted its course 
into the north channel, (the quantity of water in the latter stream being 
shown, by gauging, to be three times that in the former one), overflowing 
its banks in many places, and seriously injuring the navigation of the river 
by the amount of shingle brought down by the freshes. At the same time 
the river has threatened to break through its banks about nineteen miles 
from Christehurch, and to flow down to that town along channels which, 
although long since dry, at some distant time have carried no inconsiderable 
quantity of water. 
It is impossible to over-estimate the value of a continued series of obser- 
vations made from year to year to ascertain the nature and extent of the 
changes going on in the courses of our rivers, and I would earnestly request 
each of the members of the Institute to assist, so far as lies in his power, by 
making careful measurements, from permanently fixed points, of all altera- 
tions taking place in his own immediate neighbourhood. 
ÅRTERIAL Draryace.—Passing from natural to artificial winks 
