XXXll 



breakwaters at its enti'ance into the sea 

 to keep open a channel through its bar, 

 but the breakwaters were placed too 

 close together, and the consequence was 

 that I was in a steamer going eight knots 

 trying to get out to sea, and not l)eing able 

 to stem the Hood tide rushing in, we had 

 to turn back and wait 1 ill it slackened ; the 

 other result was that the range of tide in 

 the lagoon diminished by about ISin., 

 which was a very serious loss of tidal 

 water calculated over 1),()UU acres. 



In tlii-^ case it is certain tliat 1,200ft. 

 wide, if it attains a depth of 21ft., will 

 pass more water into and out of Macquarie 

 Harbour than at present does so, but 

 that is provided the channel through the 

 shoals above Bonnet Island are deepened 

 correspondingly ; it is hoped that this may 

 be effected by a long training-wall extend- 

 ing upwards for three miles from Mount 

 Wellington as shown on the plan ; l^ut if 

 this north channel refuses to scour out to 

 a sufficient width and depth it must be 

 touched up with a sand pump diedge. 



The style of breakwater to be constructed 

 is the old-fashioned embankment of rubble 

 stone, heavy I'ocks being j)laced on the 

 sides exposed to the waves. 



If rock of suitable size is to be had, no 

 one would dream of liuilding any other 

 kind of wall, because a rubble mound is 

 far cheaper and safer than one of concrete. 

 Of course, if stone of sufficient size cannot 

 be got, other means must be taken, such 

 as to build the mound up to half-tide level 

 and cap it with loose concrete blocks, of 

 weight sufficient to resist the waves ; but 

 I have seen uo reason to suppose that 

 there will be any difficulty in getting 

 enough rock of suitable weight. 



There is one inconvenience in building a 

 rubble mound on loose sand, which is, that 

 the waves and currents plough out the 

 sand in front and at the sides of the 

 mound, causing the stone to sink down 

 into the holes thus made. This, of course, 

 consumes a great quantity of stone, and 

 no one can tell exactl}^ how much extra 

 stone will be thus required, the only thing 

 one knows is that the influence of the 

 waves can only extend a certain depth 

 down, according to the height of the wave, 

 and beyond that the sand will be undis- 

 turbed, and the stone will sink no further. 

 In America, chiefly, they trj^ to save stone 

 by paving the leases of the mound with a 

 thick mattress of brush fascines ; this has 

 succeeded in some places, and has failed 

 and been abandoned in others ; but in this 

 country the cost of making and laying 

 such mattresses is probably greater than 

 that of the stone you seek to save l)y their 

 use. In Westport, they tried to save the 

 greatquantity of stone which wasconsumed 

 in this so-called "settlement" by pushing 

 staging ahead, and paving the bottom 

 with small rubble, but it was very uncer- 



tain whether any good was effected by this 

 method, so that it would appear that the 

 only thing to be done is to grin and bear 

 this annoying settlement of stone in the 

 sand, with the comfort of knowing that 

 vvhen your foundations have sunk to their 

 limit tlie edifice will stand for ever, in sj^ite 

 of the warning given in the Bible about 

 building on sand. 



One might naturally be tempted to 

 launch out into the most glowing antici- 

 pations of all that will come about when 

 the breakwaters are completed, and Mac- 

 quarie bar deepened to allow great 

 navies to enter into this grand harbour, 

 but it does not become me at this time to 

 dilate on these ti-iumphant fancies. The 

 apotheosis of the engineer comes in when 

 his work is finished, and until then he 

 holds his peace and devotes his care and 

 thought to seeing that the work is carried 

 out diligently and properly, so as to ensure 

 a successful completion. Let me, how- 

 ever, conclude this with the grand lines 

 from Pope, which I hope the people and 

 Government of Tasmania will take to 

 heart : — 



" Bid Harbours open, pnblic Ways extend, 

 J^id Temples, worthioi* of the God, ascend ; 

 Bid the broad Arch the riang'rous Flood contain, 

 The ii'Ole projeeted break the roarina: Main ; 

 Back to his bounds theii- subject Sea command, 

 And roll obedient Rivers through the Jjand : 

 These Honours, Peice to happy Britain brii.gs, 

 These are Imperial v\ orks, and worthy Kings." 



The paper was illustrated by over 40 

 specially-prepared lantern slides, supplied 

 by Mr. J. W. Beattie, hon. photographer 

 to the Tasmanian Government, and ex- 

 plained by Mr. Back. 



Hon. C. H. Grant, M.E.C, thought that 

 the Society and the public were to be con- 

 gratulated on having such a very able and 

 interesting paper supplied for this meet- 

 ing, and by an engineer who had the 

 highest reputation for harbour works of 

 any in the Australias. Mr. Napier Bell 

 had been professionally consulted by the 

 Governments of all these colonies, and his 

 advice was entitled to the most favourable 

 consideration. He had not been content 

 with receiving reports from other engi- 

 neers as to the peculiarities of the 

 tides and their surroundings at Mac- 

 quarie Harbour, but had resided at 

 Macquarie Heads for several weeks and 

 made the most careful personal in- 

 vestigation into all the conditions before 

 perfecting his plans. We are, there- 

 fore justified in having full confidence as 

 to the result of their being carried out, and 

 it is to be hoped that not alone the partial 

 works at present provided for, but the 

 whole scheme will be completed. The 

 resovirces of the Western District justi- 

 fied the proposed expenditure. He 

 (Mr. Grant) had seen similar works, 

 but on a much more extensive scale, 

 made universally successful in various 



