202 REPORT — 1855. 



This third and intermediate kind of knowledge, is that for the advancement of 

 which this Section of the Britisli Association was established. 



It enables its jiossessor to plan a structure or machine for a given purpose without 

 the necessity of copying some existing example — to compute the theoretical limit of 

 the strength and stability of a structure, or the efficiency of a machine of a particular 

 kind— to ascertain how far an actual structure or machine fails to attain that limit, 

 and to discover the cause and the remedy of such shortcoming— to determine to what 

 extent, in laving down principles for practical use, it is advantageous, for the sake of 

 simplicity, to deviate from the exactness required by pure science ; and to judge how 

 far an existin? practical rule is founded on reason, how far on mere custom, and how 

 far on error. 



Of those advantages, the more eminent of the designers and constructors of great 

 works of mechanical art are well aware, and have extensively availed themselves ; 

 but much still remains to be done towards impressing the general public with a due 

 sense of the mutual dependence and harmony between sound theory and good prac- 

 tice; and towards the attainment of this object, it cannot be doubted that the pro- 

 ceedings of this Section of the British Association have been and will be of important 

 service. 



Another benefit, towards which the proceedings of this Section are conducive, 

 arises from the fact, that in many cases the best, and in some cases the only means 

 of impressing on the public mind the truth and the importance of scientific principles, 

 consists in their practical application, which thus re-acts beneficially on the diffusion 

 and the appreciation of theoretic knowledge. 



There is also a beneficial reaction of practice upon theory of a different, but a not 

 less important kind ; and that is, when the progress of the mechanical arts either 

 suggests problems for scientific investigation, or aftbrds data for their solution, or 

 leads to the improvement of the instruments of scientific experiment. 



Fifteen years since, there was established by the Crown, in the University of Glas- 

 gow, a Chair of Mechanics, whose history well illustrates the prejudices which for- 

 merly prevailed on the subject of the connexion between theory and practice, and the 

 extent to which those prejudices are disappearing. That chair was not establislied for 

 the teaching of purely theoretical knowledge, which had been already well provided 

 for by the older chairs of the University. It was not for the teaching of purely prac- 

 tical knowledge, which can be acquired by experience in business alone. An impres- 

 sion seems to have at first prevailed, that the chair was of no use ; and in consequence, 

 the attendance (notwithstanding the great ability and energy of the Professor, Mr. 

 Lewis Gordon) was at the outset so small that he was induced for some sessions to 

 discontinue his lectures. But, taking into consideration the progress which a due 

 appreciation of the advantages of practically applied science had made of late years, 

 Mr. Gordon resumed his lectures last winter, and obtained at once a numerous at- 

 tendance of students, who showed, without exception, an earnest zeal to profit by his 

 instructions. That chair bears the same relation to the Chair of Natural Philosophy, 

 which Section G of the British Association bears to Section A. 



These general statements of the advantages of that kind of knowledge which it is 

 the business of this Section to advance, will, I trust, be amply illustrated .by the pro- 

 ceedings of the present meeting ; for I am happy to be able to state, that the papers 

 which will be laid before us are numerous and interesting, and in short, such as 

 might be expected at a place of meeting whose neighbourhood is well known to abound 

 in striking instances of the successful application of mechanical science to practice. 



For the discussion of that subject a more appropriate scene could not be found than 

 this University, whose walls afforded shehev, and whose inmates, invaluable friend- 

 ship, to the early days of obscurity and toil of him who afterwards showed to the 

 world the brightest example of that combination of practice and science which it is 

 our aim to promote — James Watt. 



On Railways and their Varieties. By W. Bridges Adams. 



The object of this paper was to point out the importance, and in some cases the 

 necessity, of adapting a classification and construction of railways, with reference to 

 their peculiar traffic. It was shown, that on railways with frequent trains, it was 

 unsafe to travel at different rates of speed ; and that the high speed deemed essential 



