—— 
43 [ 26] 
no water can be expected in the dry season. Mr. Speyer had taken the first 
road; our company preferred the second, because we had but four small 
wagons along, and we would gain from 20 to 30 miles travelling by it. 
From want of water we had nothing to fear, as the rainy season had com- 
menced, ane daily showers provided us with a greater abundance of it 
than we 
. On the first ‘day we started rather late frora Paso, but yet made 24 miles 
without rest. To our right was a mountain chain running, probably of 
limestone: to our left, the receding valley of the Rio del Norte, which takes 
here a southeastern direction, and from which a high chain of mountains 
will soon separate us entirely. Our road passed over a wide sandy plain, 
covered with mezquite, and similar ead . It was strewn dey two 
kinds of limestone; the one of the e character as I had seen in Paso, 
and the other of a chalk-like pe ainrre , probably a fresh-water finest 
Pieces of the first were frequently enveloped by a white crust of the latter. 
e camped near the road in the Lecaee with tolerable grass and plenty of 
rain-water. 
August 16.—Travelled this morning but eight miles, and halted, with 
d rain-water. Ahead of us were the much-dreaded. sand 
hills, (Zos medanos,) an immense field of steep sand ridges, without shrub 
or vegetation of any kind, looking like a piece of Arabian mgt. trans- 
planted into this plain, or ‘like the bottom of the sea uplifted from the 
deep. Several springs, I am told, are found near the sand hills; ta it is 
not at all unlikely that this whole round was once covered by a lake. 
One spring in B perenlay, forming a Bs hole at the foot of the sand hills, 
and called 0 malayugque, is “known as a usual cam ing place on our 
road, but 8 ge ee before reaching it. .Though we shall pass but the 
lowest eparersion of the hills, near their western limit, it will neverthe- 
lemastei hard day’s work, and we prepared our animals for it by a ‘oe 
oe noon, while we were encamped, a thunder-storm. came on, 
usual in the rainy season. It rained awhile, and towards the end of the 
shower, the thunder disappearing in the distance, I perceived a most re- 
markable phenomenon in the mountains to our right, about 10 miles dis- 
tant. Three pointed sgt apparently from one to two feet high, and of 
whitish lustre, were seen at once on a high barren place in the mountains; 
they lasted for about 10, Rae » and disappeared then as suddenly. The 
Mexicans told me that this phenomenon is not uncommon in these moun- 
tains, and that such a place had Bee been examined, and a crevice found, 
around which the grass was bur The ular opinion amongst the 
Mexicans seems to be, that such eae indicate silver mines. There can 
be hardly any doubt that the pl ni ; but 
whether a th £ awe. 1S ignited ee. y light- 
ning, or o unusual quantity of he electricity is developed by local causes, 
or superficial metallic layers should have some influence in producing it, 
are, questions’ that can only be be solved by a repeated and careful examina-— 
tion of the localities and circumstances, In the afternoon we commenced - 
our march for the sand hills. For six miles we had to travel over a eo 
and hilly County, before we reached the sand hills proper, which are here ~ 
re ti On the first part of the road I saw rocks of a jish— 
bre e aEq wo pvp, we gs sometimes Abend chalk-like g limestone, t Lid 
