J. L. Smith— Chromite from Cohahuila. 461 
our plot — pa efforts to make expansion, and a shuffling of the Be mi 
to for 
heric stra must not, however, in our ignorance, attempt 
Pactivon: in o ition facts, and if these can be satisfied more easily pe 
ater probabilites in its favor by the aid of the hypothesis of an electric 
attraction of _ sun, that hypothesis will have a better claim to acceptation than 
e othe all here note a few facts which cannot be explained by thermi 
on 
1, I have shown that on the average of many years’ sayin d in our ae 
the mean bln diminishes at the rate of 0/038 of mercury for every one hun 
dred miles we Seka eed h. This has sects called a heat froth 
the similar ay slopes: but it is lope, it is a . 
term used in railway sl : no slope, it is a lev 
surface of equim like that of the sea. Itisthe mean hights of the baro 
at the sea- oe which indicate the form, if we may so say, of the ehuitbrating 
ospher 
we have seen that the atmospheric pressure oscillates at each station 
even when the ese are quite near to each other eee ndently of the known laws 
of equilibrium of gases. When we turn to the mi-diurnal oscillation of the 
her i ation 
without peop currents “for days together, the barometer rises and fal 
tenth of an i wice in tw pik nts hour ‘2 with the regularity of the solar clock. 
Hen nt : é 
Art. LVIL—Occurrence of a nodule of Chromite in the intervor 
of compact Meteoric Iron from Cohahuila ; by J. LAWRENCE 
Smiru, Louisville, Ky. 
THE masses of iron from Cohahuila that I have designated 
the Butcher Meteorites,* to distinguish them from other me- 
teorites of the same locality, have already afforded me several 
most interesting and novel results; among them, concretions of 
surrounding conditions), and, more particularly, the new and 
Interesting mineral, Sanpréeliter sacoaiee te in the interior of the 
troilite nodules that exist in this ir A great number of sec- 
tions have been cut _ dacbreclies is always found with its 
well defined characteris 
Recently I hav sae aus two additional inne sections. 
They have furnished, however, but few nodules. e of these 
was a well-defined, symme etrically oval nodule, 17 mm. by 12 
mm., its diameters situated 6 centimeters from the exterior sur- 
face, eo nia tag solid iron intervening between the surface and 
* This pine ii, Nov., 1871. + Ib., xvi, Oct., 1875. 
