'70 Capt. McKoiiochie o}i the most effectwe Uae of 



ever, well be taken in tug-boats; it is known to all who study 

 the subject, that it might be tsaken anywhere now with safety *, 

 and the prejudice might in time lie entirely overcome. 



13. And, lastly, it may be observed, that in a navigable river 

 an establishment of steam-tugs, of which the inherent principle 

 of management was that one should always be to spare, 

 might be a most interesting acquisition in many ways, besides 

 the mere maintenance of the ferry to which it was attached. On 

 many occasions tugs might most essentially serve mercantile 

 interests ; in cases of shipwreck in particular, from their great 

 power, and comparative lightness of draught and construction, 

 they might be invaluable in laying out anchors, and in saving 

 life and property ; and although such views are not so properly 

 addressed to public bodies of trustees, incorporated for one pur- 

 pose, and for no other, as to private speculators, yet they may 

 not be without their value too. A great public acquisition would 

 thus obviously be made ; — an establishment organized with this 

 farther view, together with a ferry (particularly if bound to up- 

 hold that ferry under a pecuniary obligation), would probably 

 consist of three or more tugs, instead of two only ; — on many 

 occasions the ferry would itself reap the benefit of this additional 

 strength : — and if any, or all, of these considerations would fix 

 the attention of trustees generally on the superiority, in some re- 

 spects, of a private, over their own public management of such 

 concerns, a great step, it is confidently believed, would thus 

 alone be made towards their improvement. The very circum- 



* The improved safety high-pressure boiler is composed of a number of 

 small separate tubes or pipes, little otherwise connected than as they all dis- 

 charge their steam into one common receiver, towards the production of one 

 common effect. From their small size, they are stronger than a larger vessel 

 could well be made ; and if even one of them does burst, it has no momentum^ 

 can do no mischief, and the engine is in no degree deranged, as it only loses 

 the steam generated in the one pipe. The whole apparatus is in fact safer 

 than an ordinary low-pressure boiler ; the security of which does not consist 

 in its strength, relatively to the pressure to which it is exposed, but in what 

 is above adverted to as the radical defect of the engine for the purposes of 

 navigation. It has no power in reserve, consequently holds out no tempta- 

 tion to the engineer to subject the boiler to a severe trial. But if that is ne- 

 glected, it will burst like the worst construction of high pressure boilers, and 

 do nearly as much harm ; as was proved by the explosion of the Graham 

 alongside the United Kingdom, two years ago. 



