MEETING OF THE BRITISH ASSOCIATION. 123 



of fishes or reptiles. — Mr. Snow Harris read a paper on the electri- 

 city developed in the evaporation of water. He undertook to prove 

 the electric matter is developed where pure water is evaporated. Mr. 

 Harris exhibited an extremely delicate apparatus, or electrometer, 

 which is affected at twenty feet distance from the plate machine.— 

 The gold leaf was strongly affected, at a distance of several feet, by 

 a glass rod slightly rubbed with a silk handkerchief. 



Section C. — Geology mid Geography. — Lieutenant Stotherd 

 read a paper on a small granite district in the county Cavan, sur- 

 rounded by the transition series, and the primary rocks. — Professor 

 Phillips made a communication relative to the Belemnites. — Profes- 

 sor Agassiz, one of the most eminent of the continental geologists, 

 who spoke in French, observed upon specimens he had seen in 

 France, with the cuttle at the end of the shell filling up the cavity 

 observable in the British specimens ; whether this arose from a va- 

 riety in the species, or what other cause it was not stated. Profes- 

 sor Phillips urged, in eloquent terms, the great advantages of theo- 

 logy, and the importance of examining fossil remains. — Captain Den- 

 ham, R. N., one of the officers attached to the ordnance survey of 

 Great Britain, exhibited a map illustrative of the estuaries of the 

 Dee and Mersey. He exhibited a chart of these two rivers, and a 

 tide-table, so calculated that the mariner may know any half-hour 

 the banks which might be crossed ; thus pointing out the danger, and 

 when it ceased — a matter of great relief to the mariner. Captain 

 Denham complimented the Dock Trustees of Liverpool, for their 

 munificent expenditure, in enabling him to prosecute his object, and 

 dwelt with particular stress on the unbounded liberality of Sir John 

 Tobin. Captain Denham suggested the utility of establishing a 

 half- tide level at each port, to point out the soundings of banks at 

 the half-tide along the continuous shore. The gallant Captain 

 next alluded to the error which had nearly been committed in cut- 

 ing a canal from Bridgewater to the sea, when there were tides 

 from fifty-six feet level to eighteen feet. He observed that if the 

 distance from the earth's centre to the half-tide level were calculated, 

 it would form a correct base for ascertaining the heights of the land. 

 It would form a matter for consideration if the influence of the sun 

 and moon on the tides were withdrawn, whether or not the water 

 would recede to the half-tide level — (loud applause greeted Captain 

 Denham at the conclusion of his observations). Professor Sedg- 

 wick and Sir John Tobin severally offered a few observations com- 

 plimentary to the exertions of Captain Denham, and of the ability 

 with which the map and tide tables were executed. Professor Grif- 

 fiths moved the especial thanks of the section to Captain Denham, 

 which was enthusiastically responded to by the crowded and intelli- 

 gent audience. Professor Murchison said this showed the intimate 

 connexion between geology and geography. If this subject were 

 followed up with that spirited enterprise displayed by such gentle- 

 men as Sir John Tobin, and others, the elurement of land in one 

 place and its increase in another, might yet be defined, and the 



