ADDRESS. xlix 



$hare of the attention of this Association. The former, indeed, when it is 

 made to include experiments on Tides and analogous pheenomena, becomes 

 almost one of the cosmical instead of one of the constructive sciences. It 

 would be an endless task for the most accomplished mechanic to attempt to 

 describe to you the inventions which are constantly made in every part of 

 manufacturing science. Confining myself to engineering science, I may 

 state, that in the present partial suspension of railway works, and since the 

 great achievement of the raising of the Britannia Bridge, there appears to be 

 little which has strongly fixed public attention. Considerable importance, 

 however, is attached by engineers to some of the processes lately introduced, 

 — especially that of thrusting down an air-tight tube or elongated diving- 

 bell, supplied with air at the proper pressure, by which men are enabled to 

 perform any kind of work under almost any circumstances, and in which 

 men or materials may be transferred without disturbance of the apparatus, 

 by a contrivance bearing the same relation to air which a common canal-lock 

 does to water. Improvements have also been made in the application of 

 water-pressure to various mechanical purposes. Some years ago, an exten- 

 sive inquiry into the practical uses and properties of various metals was 

 made by a Committee appointed by the Board of Admiralty. It appeared 

 to the Association a matter of great interest that the Reports of this Com- 

 mittee should be published ; and, on their applying to the Admiralty, in- 

 structions were immediately given for placing the original Reports in the 

 hands of the Council of the Association. The Council have requested Mr. 

 James Nasmyth to draw up an abstract of the principal contents of these 

 Reports ; and this abstract, I hope, will be presented to the present meeting 

 of the Association. Other Reports on important engineering subjects, for 

 which requests were made by the General Committee at the Edinburgh 

 meeting, will, I trust, be communicated to the present meeting. In treating 

 of Practical Mechanics, I may perhaps with propriety allude to the investi- 

 gations which have lately been made by able engineers regarding the Me- 

 chanical Equivalent of Heat. The subject, in this form, is yet new ; but I 

 think that the importance of an accurate determination cannot be overrated. 

 This also appears the proper place for alluding to a subject which has at- 

 tracted the attention of the Association from its very first formation — namely, 

 the simplification of our Patent Laws. The measures of the Government on 

 more than one occasion have shown that they are desirous of removing the 

 inipediment which, in this country (strange to say) more than in any other 

 in the world, have been placed in the way of mechanical inventions. 



I cannot quit the subject of Manufactures without alluding to a thing 

 which is, so far as I know, perfectly unique in the history of the world,— I 



