ON HARBOUR WORKS. 
By H. Shklford Bidwell, C.E. 
Harbour Works . — The term “ Harbour Works,” which has 
been set down as the subject of the paper which I am to read to 
you to-night, covers a somewhat wide range ; wider than could 
be dealt with in detail within the limits of a paper such as this. 
I propose therefore to divide my subject into two heads, viz. : 
(1) Harbours of Refuge ; 
(2) Commercial Harbours ; 
and to give a short description of works undertaken for 
these purposes. 
Preliminaries.— -Whatever may be the class of Harbour 
that it is desired to make, the first step is to have an accurate 
survey made of the proposed site, including soundings, observa- 
tions of tidal and other currents, range of tides, direction and 
height of waves, direction and force of the most prevalent winds, 
and so on. It is usually desirable also to take borings at inter- 
' al » over ground upon which it is intended to place any struc- 
ture, in order to ascertain the composition of the bottom for some 
depth. I need not of course describe the method of taking 
soundings and borings, but perhaps a short description of tidal 
current observations may be interesting. For these a float or 
uoy of wood is made, somewhat in the shape of the feather-end 
o an arrow ; it is weighted at one end so as to float in an up- 
jjjpt position and to the other end a small flag is usually attached. 
06 observer places the float in the water at a known spot, and 
w lows its course in his boat, fixing its position at intervals by 
taumg angles with the compass or sextant between known 
objects on the shore. On the Tyne Harbour and River Works, 
* lore I was employed for some years, a very elaborate set of 
*udi observations were made every five years in order to ascer- 
ain die effect of the elongation of the Piers at the Mouth of the 
"Of upon the currents within the Harbour. There, besides 5 
w 6 observers with their floats, there were lines of anchored 
7 s from the mouth of the River to a point some miles up 
m. and on these were men employed in taking and recording 
irength of the current at their respective stations; while 
7 rs were stationed at the various tide-gauges along the nvei 
? ot ‘ng die rise and fall of the tide. These observations continued 
7 weeks, trips with the float being made 4 times on the 
f°° a “ feand the same on the ebb ; and as work was c J , " 1 " Qen ®^ 
0r before dawn and continued till after ar ’ " 
0D f our floats painted with luminous paint, to e “ able US J7 
See in at these times.— Of course at these times it was not 
