Report of Meetings. By the President. 455 



As the slits or openings come opposite to each other the com- 

 pressed air escapes through them, producing 20 x 24 = 480 dis- 

 tinct shocks, vibrations, or sound waves a second — that is, 

 28,800 a minute — which, following each other in such rapid 

 succession, fall on the ear as a continuous sound, that is pro- 

 jected seaward through a huge trumpet, which is always turned 

 to windward when in use. Under favourable circumstances the 

 trumpet can be heard 12 miles off. 



The Syren is the result of a long series of exhaustive experi- 

 ments, which have proved it to be the form of instrument which 

 can be heard at the greatest distance, though in the immediate 

 vicinity sounds produced by other means may be louder. 



The Keepers observe a rule that as soon as they lose sight of 

 the Pinnacles in thick weather they begin sounding the fog-horn. 



The Fames present so much that is interesting that we all 

 felt, with regret I believe, how little justice could be done to it 

 all in the course of so brief and necessarily hurried a visit. 



We had no time, for instance, to examine the geological 

 features in anything like detail. Geologically speaking, the 

 Fames are an outcrop of the Great Whin Sill, with remains of 

 sedimentary rocks containing fossils, and boulder clay. There 

 are marks of glaciation to be observed. 



The Great Whin Sill was a vast subterranean lake of melted 

 Basalt, which, at some time during the Carboniferous Period, 

 many long ages ago, — who can tell correctly ? — was forcibly 

 intruded among the lower Carboniferous strata of Northumber- 

 land. It never reached the surface, but cooled between the 

 sedimentary beds ; which, since worn away by denudation, have 

 here and there exposed it to view, and it forms the surface or 

 nearly so ; as at Embleton whence we get whin-stone sent to 

 Berwick for our road metal; at Spindlestone, where it forms 

 the celebrated Craigs of that name ; and at Dunstanborough and 

 Bamborough where the Castles stand upon it. 



Now this enormous sheet of igneous rock which ranges from 

 20 to 150 feet in thickness, is known to stretch across a great 

 portion of Northumberland^ and probably underlies the whole 

 of the Southern and Eastern portions of the County, is not, one 

 must note, an ordinary intrusive dyke, passing vertically through 

 the strata as at Holy Island and other places. Neither is it a 

 regular "interbedded trap," or stratum which once formed the 

 surface, and on which other beds were in due course deposited, 



