Rev. T. G. Bonney — Pitchsfones and Felsites of Arran. 511 
with libe, in alternate Order. 1 The effect then of contraction due to 
cooling is probably mach greater in producing rock structures than 
has been generally supposed. Since, however, the Chemical com- 
position, and the circumstances of solidification, vary so greatly in 
igneous rocks, and a very slight difference in the circumstances may 
produce with these minute structures a very appreciable alteration 
in the results, we must not be surprised if cases sliould occur to 
wliich we cannot apply the above explanations, at any rate without 
considerable modification. 
IV. — Across Europe and Asia. — Travelling Notes. 
By Professor John Milnb, F.G.S. ; 
Imperial College of Engineering, Tokei, Japan. 
(Continued from p. 468.) 
Part VI. — Tomsk to Irkutsk. 
Contents. — Tomsk to Krasnojarsk— Appearance of tlie Country — Flint Implements 
at Kansk — Pre-historic Remains in Siberia, probably the ‘ Spoor ’ of a race 
allied to the Eskimo— Geology in the neighbourhood of Irkutsk — Cold of 
Irkutsk. 
T HE day on whicli I arrived at Tomsk, which was the 6th of 
October. I bought a small tarantass, and next morning I started, 
with some who had been fellow-passengers on the steamer, en route 
for Irkutsk. There were four conveyances between three parties, 
one of them being used exclusively for baggage. As each of these 
always needed three horses, and sometimes four, we often had diffi- 
culties at the post-station, where the post-master seemed disinclined 
to allow such a sudden draft being made upon bis stables. Luckily 
my friends were high officials, and travelling on Government Ser- 
vice, and their wants liad from necessity to be supplied. My 
carriage being included with the rest, I went along comfortably and 
without delay, which would most oertainly have occurred had I 
been alone. Before we were fairly outside Tomsk we ascended 
what I had, when at a distance, mistaken for hills, but which now 
appeared to be only a scarp-like face of a plateau, and we were soon 
upon a dusty road bounded by a low plantation of birch. Now and 
then we plunged down and over a small water-course, our momen- 
tum always carrying us some distance up the other side. Every- 
where the country appeared as if it were an alluvial expanse ; but in 
the vicinity I think there must have been some beds of rock, because 
everywhere along the road stone was being used as a material to 
repair it. Tliis was yellow, argillaceous, and somewhat slaty in its 
character, perhaps having come from some of the Coal-measures 
which I believe exist in the vicinity of Tomsk. The birch-trees 
were now destitute even of their withered leaves, and the only 
relics of the falling year were a few white heads of a Millefolium 
and brown tufts of faded grass. Düring our first day upon the 
road we met a number of carts carrying a white clay, used in Tomsk 
for the manufacture of pottery. We travelled day and night, stop- 
1 With this compare the “ veined structure” in glacier ice, as explained by Prof. 
Tyndall, Glaciers of the Alps, p. 376. 
