SIR JOHN HERSCHEL’S RESEARCHES AT THE CAPE. 
333 
having been rendered dry during many weeks 
in ihe height of summer, the mud, in drying, 
was immediately and entirely covered, to the 
extent of many square yards, by a minute, 
compact, green turf, formed of an impercep- 
tible moss, the thaseum axillare, the stalks of 
which were so close to each other, that upon 
a square inch of this new soil, might he count- 
ed more than five thousand individuals of this 
minute plant, which had never previously been 
observed in the country.* 
BAROMETRICAL OBSERVATIOxNS, 
By Sir John Herschel. 
BAROMETRIC COMPARISONS.— Sir 
J. Herschel’s fine mountain barometer having 
been accurately compaied with the Standard 
barometer of the Royal Society, accompanied 
him in an extensive scientific tour which he 
made through France, Germany, Switzeriend, 
Italy, and Sicily, and was on that occasion 
succesively compared with the other barome- 
ters in the principal observatories of Europe. 
On his return to England it was again compar- 
ed with the Standard of the Royal Society, 
and although it had ascended with Sir John to 
the craters of Vesuvius and Etna, (in the latter 
case “ under circumstances very trying to the 
instrument,”) it was found to give the same 
difference within the three-thousandth of an 
inch as that obtained in the first instance be- 
fore setting out. 2. In 1832, the same moun- 
tain barometer was lent to Professor Hender- 
son, on his going out as Astronomer Royal 
to the Cape, and, having been compared both 
on setting out, and again in the following year 
on his return, the second difference was on this 
occasion the sameas in the former case, — name- 
ly, only the three-thousandth of an inch. 3. Be- 
fore Sir John Herschel’s leaving England in 
1833, it was again compared with the Royal 
Society’s Standard, (giving the same diffeience 
as before,) and, on his arrival at the Cape, 
was compared with the barometer of the Roy- 
al Observatory in that colony ; the determi- 
nation of altitude in this latter instrument, as 
compared with the Royal Society’s, by the 
intermedium of the mountain barometer, be- 
ing the same within the five-thousandth of an 
inch as made on the former occasion by Pro- 
fessor Henderson ; the mountain barometer 
having, in the course of these comparisons, 
made three voyages to and fiom the Cape. 
EQUATORIAL DEPRESSION.-Sir 
John Herschel, in the observations made dur- 
ing his voyage out to the Cape, remarked the 
interesting phenomenon, that “ the barome- 
ter under the Equator has a lower mean alti- 
tude than in north or south latitude, and that 
the increase of altitude is steadily maintained 
at least as far as either tropic— the equatorial 
depression amounting to about two-tenths 
of an inch. The physical cause is not far to 
seek. It consists in the upward suction, 
which is the immediate consequence of the 
overflow of the equatorial atmospheric column 
into the extia-tropical regions, and which is 
♦ Jameson’s Journal, No. 39. 
not immediately compensated by the under- 
current of the Trades. It is a dynamical re- 
sult, into which time enters as an essential 
element. In this (as in the tides) equili- 
brium is not established instanter, and this 
gives room for the development of appie- 
ciable differences of tension in diffeient parts 
of ttie circuit.” 
BAROMETRIC FLUCTUATION— Sir 
John Herschel states tlrat he has, since his 
arrival at the Cape, been collecting data for 
an inquiry into the laws of barometric fluctua- 
ation in those regions, and, having fortunately 
met with a fine series of fifty-seven months’ 
observations by Capt. Bance, registered in 
Cape Town, he has undertaken the labour 
of reducing them. “They exhibit an ex- 
tremely regular fluctuation of three-tenths of 
an inch, by which the barometer stands higher 
in July than in January. On the other hand, 
by the Calcutta Registers, as published by 
Priusep, for the last two years and a half, 
it appears that the reverse obtains there,— the 
barometer standing higher in January than 
in July by about ‘5'i inch. Thus, it appears 
that there is an annual bodily transfer of a 
certain considerable mass of air from hemi- 
sphere to hemisphere ; and of this, too, the 
cause is obvious, being the more heated state 
of that hemisphere over which the sun is 
vertical, in comparison with that on which he 
shines obliquely.” 
FOOT-MARKS OF UNKNOWN ANI- 
MALS AND BIRDS IN NEW RED 
SAND STONE. 
Our geological readers are familiar with 
the description, by Dr. Duncan, of the traces 
of animal impresstions in the new red sand- 
stone of Dumfries-shire. Traces of un- 
known animals have recently been detected 
in a similar rock, at Hildburghausen, inThu- 
ringia, by M. Lickler. Traces of four spe- 
cies of different animals can be observed. 
Two footmarks are always found together ; 
one behind about six inches long, the other 
before, only half as large. The toes are five. 
The large toe is situated at a right angle in 
relation to the others. The two large toes 
of one pair of feet are directed always from 
the same side, but the same toes of the fol- 
lowing pair are directed in the opposite way. 
The animal must, therefore, have ambled. 
A remarkable feature is, that the pairs of feet 
follow in a right line : — lienee the animals 
must, when they walked, have raked the 
earth. Count Munster considers them to 
have been amphibia ; Weiss, on the contrary, 
mammiferae ; while Link beleives them to 
have been gigantic sauri, like the chameleon. 
— (Bihliotheque Universelle, 1835, vol. ii. 
399.) 
The first traces of birds, however, in a 
similar situation, have been discovered on the 
banks of the Connecticut river, in Massa- 
chusetts ; and described by Professor Hitch- 
cock, of Amherst College. The appear- 
ance presented is that of the feet of a bird 
which had been walking in the mud. The 
