¢ 
354 
getitices the length of the archway sd 
Puch, that it will not exceed 300 yards, 
‘Rit whiere, from the diversity of the scene- 
“~~ and extensive views, the beauty of 
ie line will be exceedingly great, has 
Hiready produted the effect of reconeiling 
the tninds of those who so violently op- 
osed its The entratice to this road from 
Filton is immediately at the foot of 
the bill in Upper Holloway, Tt com: 
Hiences by a deep curcing on the right of 
‘the present line of road, which is conti- 
fiued, encreasing in depth, until it feaches 
the intended archway, a distance of 550 
yatds, where tlie vertical heizht of the 
“surface above the line of the road is up- 
®ards of sixty feet. This open cutting is 
‘wearly completed, the slopes on eath side 
6f the foad ate cultivated and fenced 
with osier, holly, and hawthorn, and pre- 
sent a pleasing entrance to this greatwork, 
‘The archway is not yet completed: but, 
fs an auxiliary, however, a drift has 
bech cut, (an upening 44 feet wide and 
# feet hivh) through this wing of the 
hil}, by which means the favourable qua- 
dity of the earth has been ascertained. 
iis drift was executed by sinking per- 
penticularly three shafts or wells, from 
the surface to the level of the intended 
foad, at the distance of one hundred 
$ardls apart, and from the bottom of each 
“a direct line was formed to the extre- 
tulties of the hill. From the information 
i fave been able to procure, it appears 
that the arch will be the segment of an 
tllipsis, having its longer axis vertical 
fwetity-eight feet, and its shorter axis 
horizontal twenty-four feet, the under 
part of the arcli being drawn to a radius 
OF twenty-six Teet. The space for car- 
rineés and foot passengers to pass each 
Other, will be twenty-four feet in width, 
nd twenty feet in height. The sur 
‘founding earth will be supported by brick 
@nd° iron work so firmly cemented, 
@s td become one solid mass. The 
©breadth of the arch is considered am- 
ply sufficient vo admit the passing and 
repacsing of the largest earriages, and yet 
to allow a Yuot-path on each side. It is 
othe intention of: the promoters of- this 
whdertaking, to shorten theareh as much 
es the nature of the surrounding earth 
wejif” permit; and it is new confidently 
stated, that the length of the archway 
“will not exceed three humwdred yards. 
The remainder of the line, to the north 
of ihe archway, is in a considerable state 
of forwardnéss. Jt.is formed by deep 
euttings. throwgh whe! east and nortn 
wings of the hill, tae earth being depo- 
Arciway through Highgate. 
‘in forming the archway. 
_—s Ss 
[yuly 1, 
sited in the adjacent -vales, and thus aw 
easy regular ascent is preserved the 
whole length of the line, which will be 
one mile and an half. This work, ale 
though it did not commence till July 
last, is 4 4 state to create confidénce, 
that in less than twelve months the pub 
lic will be accommodated, . To rendér 
this design complete, there has been 
procured during this session, an Act to 
enable a direct line of road to be formed 
from the Assembly House, at Kentish= 
town, to the archway, This great une 
dertaking, for want of being sutliciently 
understood, was in its infancy ranked 
among some of thuse-ephemeral schemes 
never to be executed. But the prompt- 
ness and ability with which this work has 
hitherto been conducted, will in the lie 
beral and enlightened mind be an object 
of much consideration, and is highly ho- 
nourabie to those engaged init. To the. 
experimental arts, and experimental 
philosophy, the greatness of a nation 
owes much; and almost all our publié, 
works hold out a field, not only for dis. 
playing, but frequenuy an opportunity of 
Improving,» practically these important 
scrences; and hence, by such enters 
prizes, lasting national monuments: are 
raised of our strength in intellect and 
industry, The naturalist and geologist 
have, in the excavations made in these 
works, much to engave their attention, 
as the fossils are numerous and inter. 
esting. It would exceed the limits of 
this article to enter into a minute de. 
scription of them, «I shall therefore only 
enumerate a few of the most striking, 
The hill is composed: of alluvial earth, 
and different strata of clay. The stra. 
tum of brown clay is interspersed with | 
finely crystallized selenite, or gypsum, 
and the common argillaceous iron stone 
of Kirwan, or Septania,- formerly knowa 
by the name of Ludus Helmontin. These 
stones, when barnt, form a cement, well 
known by the name of Parker's cemeify 
and will prove a considerable acquisition 
In the blue 
stratum these stones are also very aburi= 
dant, brilliantly studded with pyrites, 
and often contain a variety of small 
shellse . The septa of these fossils, ia. 
both strata, are composed of calcareous 
spar, or finely crystallized carbonate of 
june, having a beautitul velvet appear. 
ance, of various hues. flere also ane 
found some fossil teeth, commonly called _ 
shark’s teeth, -Sometimes> swordfishes _ 
teeth, but onlike either; petrified fish, 
fruic er nuts, mere resembing the pals 
‘ 
nut, | 
y) 
f 
