24 ANNUAL OF SCIENTIFIC DISCOVERY. 



wrought-iron kelsons, or bulkheads, running athwart-ships. The 

 entire machinery is upheld and retained in place by these kelsons ; 

 girders they are in reality, for while they carry the engines they also 

 form a chord to the arc of the ship^ bottom and materially strengthen 

 the hull. The absence of bed plates dispenses with at least forty 

 tuns of iron, in round numbers ; for these details and their appen- 

 dages would, with engines of the usual construction, weigh that 

 amount, Avhile the absence of heavy cast-iron frames is also a source 

 of great advantage. This is particularly the case in a vessel-of-war, 

 where every pound of extra weight is a positive injury, increasing 

 the draft, the load, and adding to the labor of the ship in a sea-way. 

 The cylinders are bolted directly to the wrought-iron kelsons men- 

 tioned previously, and the power exerted within them is transferred 

 to a short rock-shaft, supported on vertical pillow-blocks, bolted and 

 braced firmly to the same kelsons : beyond this arrangement there is 

 no other. Cumbrous and heavy frames which interfere with a 

 thorough inspection of and access to the machinery, and massive bed- 

 plates, are both wanting, and the other details of the engines are 

 equally sound from an engineering point of view. Scientific Ameri- 

 can. 



ON THE MARINE ENGINES OF THE U. S. NAVY. 



In the Report of the Secretary of the Navy, communicated to 

 Congress December, 1864, the following interesting statements are 

 made respecting the use, construction, and improvement of the steam 

 machinery of the United States Navy. The Secretary says : 



As oui- navy has become not only exclusively a steam navy, but a 

 very large one, with an enormous consumption of coal and great 

 expenditure for the construction and repair of machinery, it be- 

 comes a matter of the first consequence that only the best machinery 

 be obtained for it. This problem is one of very difficult, costly, and 

 slow solution. The great maritime countries of England and 

 France have not yet solved it, either in the commercial or war 

 marine, and at this hour the best authorities do not agree upon it. 

 So many conditions enter into the problem that, as prominence is 

 given more or less to one or the other, different conclusions are 

 reached. It is evident that the question is purely a practical one ; it 

 can only be answered by extensive experience and accurate observa- 

 tions. Mindful of the importance of this matter, the Department, 

 notwithstanding the great pressure upon its resources by the Avar, 

 has kept it in view and promoted by every means the acquisition of 

 the necessary information. The proportions of hulls have been 

 varied with a view to determine the relative development of speed 

 in proportion to given power; machinery has been constructed upon 

 different types and systems, and the Department has encouraged all 

 offers from citizens, as well as from its own officers, to build new 

 machinery that gave promise of improvement. The navy at this 

 moment contains marine machinery on an extensive scale of every 

 kind ; their results are in its log-books, from which can be deter- 

 mined their various merits, both for general service and for particular 

 applications. 



In the wooden vessels of the navy nearly every variety and type 



