298 
THE GEOLOGIST. 
sudden increase of width at certain beds, as tliougli the substance of 
sucli strata was easier removed than that of others. Indeed, the 
unequally worn sm'ftice of the limestone composing the sides of the 
pipes seems indicative of the same thing ; for, on removing the 
internal core of sand or clay, and so exposing this surface, it is inva- 
riably found, so f;xr as I have examined, to be unevenly worn, some 
beds, or portions of beds, standing out in relief, and others being 
deeply corroded all round the cu'cumference. The widest pipe I have 
seen was about two feet across, but most of them are under twelve 
inches. Transverse sections are usually more or less cu-cular, oval, 
or ovate, the diameter of course varying in diiferent directions. 
Though, perhaps, the most of the pipes are excavated straight into 
the hmestone, yet several are more or less oblique. The most 
I'emai'kable instances of this kind are represented in fig. 4. In more 
than one instance I have actually seen pipes which change the direction 
of their orig'inal com-se, so as to become in a measure slightly angulated. 
I cannot but think that the dh'ection of both the latter pipes and those 
whose courses are oblique must have been determined by some pre- 
existing fissure or other weakness in the limestone, though in these 
instances I have seen no indication of any such fissures. 
The pipes are usually filled with sand from the bed overlying the 
limestone, but sometimes with sand and clay ; and occasionally a 
great portion of the core is composed altogether of clay of an unc- 
tuous and tenacious character, and which often contains numerous 
remains of small vegetable roots, or the perforations once occupied 
by such roots ; in fact, so thoroughly perforated are the cores of clay 
sometimes by the minute ra,mifications of these roots, that I almost 
believe that they would be quite pervious to water in spite of the 
impermeable nature of the clay composing them. 
(To he continued.) 
BRITISH ASSOCIATION MEETING. 
The Meeting of the British Association opened on tlic 27th of June, at Oxford, 
under the presidency of Lord Wrottesley. 
The President, in his address, ofFcrcd some admirable remarks on astronomical 
matters, and on tlie progress made in chemical science. On geology his re- 
marks were chiefly confined to the interesting to])ics of the earliest human 
remains, associated with tliose of extinct mammaUa. We give this part of his 
address entire. 
" The bearing of some recent geological discoveries on the great question of 
the high antiquity of man was brought before yom- notice at your last meeting, 
at Aberdeen, by Sir Charles Lyell, in his opening address to the Geological 
Section. Since that time many French and English naturalists have visited the 
valley of tlie Somme in Picardy, and confirmed (he opinion recently pubhshed 
by M. Boucher de Perthes, in 1847, and afterwards confirmed by Mr. Prcst- 
wich, Sri- C. liyell, and other geologists, from personal examination of tliat 
