232 Proceedings of the British Association for [Sept. 



Liverpool ; and this speed could be accelerated to 60 miles an hour* 

 At this rate we might reach Liverpool from London in three hours 

 and a half. 



A bill has been obtained to connect London and Southampton, and 

 another is about to be obtained for a Bristol rail way. 



It is pleasant to contemplate the effects of facility in communica- 

 tion. Formerly, 450 persons passed daily between Liverpool and 

 Manchester. Now, 1309 persons pass. Between London and 

 Liverpool 1350 persons pass. When the rail-road is completed the 

 number will be above 4000. 



It is proposed to have a line of road through Ireland, between 

 Dublin and Valentia, to constitute the high way to America. The 

 formation of this road, which will conduct all passengers between 

 Britain and America, through the middle of Ireland, will tend, in 

 the opinion of Dr. Lardner, to produce tranquillity and peace over 

 the length and breadth of the island. 



In America there are 40 rail-roads completed, and about 100 in 

 progress. The longest is 50 miles at present. But the Ohio rail- 

 way, now forming, is above 300 miles in length. ' 



Wednesday y \2th August. ^ 



After the reports of the sections had been read by the several 

 secretaries. Professor Powell proceeded to give a lecture on the 

 theory of the dispersion of light. 



In introducing the subject, he observed, that to many, this subject 

 might appear dry and cold, but it had a peculiar interest to those who 

 studied it, for it was prosecuting truth for its own sake. It had, 

 therefore, a high, sublime and sacred claim to attention. Its pheno- 

 mena were required to be investigated by refined analysis. The 

 study was minute, it is true, and to many, therefore, it might appear 

 trifling. But to such persons, the saying of tlie Honourable Robert 

 Boyle might be given as an answer. He was an Irishman, and was 

 the first to reduce into practice the theories of Bacon. When cen- 

 sured by his friends for engaging in occupations apparently frivolous 

 and trifling, he replied, ^' There is nothing unworthy of being inves- 

 tigated which was thought worthy of being created by God," 



The lecturer proceeded to state that Professor Airy had suggested 

 to him to compare the relation deduced from Cauchy's theory between 

 the length of a wire and the refractive index for each of the different 

 standard rays, with the numerical values of those quantities obtained 

 by experiment for different media. This he accordingly attempted 

 to do for all the ten media examined by Fraunhofer. The results 

 will be seen in the Phil. Trans, for the present year : And, it is 

 conceived the coincidences are such as to justify the conclusion, that 

 M. Cauchy's theory is established by observation as far as those media 

 are concerned. The author has since commenced a more extended 

 series of measurements of the deviations of the definite standard rays 

 for prisms of various transparent media, by means of a telescope 

 attached to a graduated circle having two opposite visions. Such a 

 series of observations is one of the recommendations of the British 

 Association ; and the author, therefore, hoped that some of its mem- 

 bers may be willing to co-operate with him should they have oppor- 

 tunities of procuring for examination some of the less common refrac- 



