THE TIDES OF SOUTH AUSTRALIA. 241 
of high or low water uncertain, the vertical slide can ke put in 
and the curve traced, the time and height can then be measured 
off. 
When one of the carriers (of which there are three) is through 
the frame it can be disconnected from the others and connected 
up again at the other end, the curves are again placed in their 
respective grooves, butting close up to the preceding ones, and so 
on, forming a continuous chain of curves. With a little practice 
this can be done expeditiously, and very little time lost. 
By means of this machine the tides for a year can be predicted, 
and a tide-table published at a comparatively small cost, because 
the time and height can be read off and tabulated at once ready 
for the printer. 
In other tide-predicting machines where the motion of each 
component is represented by an eccentric or crank and pinion, it 
is necessary to drive each wheel at a different speed, and this 
necessitates very complicated gearing. In this machine, how- 
ever, all the components are driven along at the same speed, and 
the machine is thereby greatly simplified. No matter how irre- 
gularly the handle is turned the motion forward automatically 
indicates the time. 
The machine has been tested by setting it for a year that was 
past, and the results compared with actuality. This comparison 
showed that there was a probable error of from five to ten 
minutes in time, and from 6 to 8 inches in height, which may be 
considered very good for a place where the meteorological effects 
bears such a large proportion to the ordinary rise and fall. 
No. 6.—THE TIDES OF SOUTH AUSTRALIA. 
_ By R. W. Cuarman, M.A., B.C.E., and Capt. A. Ineuis. 
(Read January 10, 1898). 
At the Adelaide meeting of the Association, we stated that we 
were then engaged in making a second analysis of the Port 
Adelaide tide curves. The work was soon afterwards completed, 
and the results of the second analysis are stated in the following 
table, side by side with the first ones. We found, however, that 
through too blindly following certain wrong instructions in 
“Baird’s Tide Manual,” that we had made an error of 180° in 
Q 
