Intdlipence and Miscellaneoiis Articles. 467 



along the north and south coasts of Strath and in the interior, par- 

 ticularly noticed the occurrence of white quartzite in the lower lime- 

 stone near Suisnish, and the limestone-breccia skirting the long 

 sandstone-ridge traversing Strath. The igneous rocks, comprising, 

 1st, the great eruptive syenitic masses, and 2ndly, the innumerable 

 dykes of augitic trap, were then described; the junctions of the syenite 

 with marble and with shale, and the metamorphism of the calcareous 

 rocks, being specially illustrated. The igneous eruptions in Strath 

 appear to have been all posterior to the middle lias ; the first period 

 of volcanic activity gave rise to a profusion of trap-dykes traversing 

 every part of the district, but not materially altering the position or 

 texture of the strata ; subsequently vast tracts of syenite tilted up 

 the lias-beds, and extensively metamorphosed them ; lastly, great 

 masses of fine-grained syenite, associated with greenstone-dykes, were 

 intruded among the beds without either tilting or altering them to 

 any great extent. 



This paper was accompanied by a note on Mr. Geikie's fossils by 

 Dr. Wright. Isastrcea Murchisoni (sp nov.), Ostr<ea arietis, and Car- 

 dinia concinna were found at Lussay : Belemnites elongatus, B. pax- 

 illosus, B. breviformis, Ammonites Jamesoni, A. brevispina, A. Davcei, 

 Trochus imbricatus, Pholadomya ambigua, Pleuromya Scottica (sp. 

 nov.), P. unioides, Unicardium cardioides, Pinna folium, Mytilus scal- 

 prum, Lima gigantea, L. Hermanni, Limea acuticosta, Inoceramus 

 ventricosus , Pecten aquivalvis, Plicatula spinosu, Gervillia Maccullochii 

 (sp. nov.), Gi-yphaa cymbium, G. obliquata, and Rhynchonella tetra- 

 hedra occur in thePabba shales. Pecten cequivalvis and Avicula, sp., 

 are described as occurring at Scalpa. 



LXII. Intelligence and Miscellaneous Articles. 



ON THE TEMPERATURE OF FOAM. 



To Dr. Tyndall, F.R.S. SfC. 



Museum of Practical Geology, 

 Dear Sir, May 4, 1857. 



YOUR remarks in the last Number of the Philosophical Magazine, 

 on the Temperature of Foam, recall to ray mind an observation 

 of a similar kind made by myself and my friend, Mr. James Simpson, 

 jun., when on a pedestrian excursion in Surrey in December 1855. 



Our attention was arrested, on arriving at the last lock on the 

 river Wey, at the distance of about half a mile from the point where 

 it empties itself into the Thames, by the production of an extraordi- 

 nary amount of foam, in consequence of the falling of the river over 

 a weir. 



This foam was not only unusual in amount, but had a peculiar 

 soapy appearance, and on dipping the hand into it was found to be 

 quite warm : fortunately we had a thermometer with us, and were 

 therefore enabled to measure the extent to which the temperature of 

 the foam exceeded that of the water on which it was formed. 



The temperature of the water was 42°5 F., whilst tliat of the foam 

 was 45°, so that the foam was 2°'5 warmer than the water. The 



