The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1836-10-14 00:00:00

A SOLITARY GLEN.

(rpox THE SCOTTISH MONTHLY MAGAZINE FOR OCTOBER.)
How all things breathe of loneliness? The flowers,
Like timid birds, seem shrinking, half afraid,
From human notice, as they had displayed
Their virgin loveliness, throu.h summer hours,
But to their gentle sisters 'mid these bowers,
In unpreturhed beauty! The dim glade,
Slumbering beneath the quiet air in shade,
Seems sacred to the tutelary powers
Of silent contemplation and deep peace :
I breathe a purer air—lifting the heart
From the low cares that torture human kind,
To hopes of higher aim, which in the press
Of thronging crowds were cabined and confined
'Mid stifling toil and dark self-seeking art.

THE DESERTED CHURCH,

No costly tables deck the wall—
No sculptured monuments are there ;
Cold, damp, and age are spoiling all
That desolated House of Prayer.
From the low porch the latch has gonel
Rude kends have marked the oaken door ;
While moss grows thickly o'er the stone,
dad rank weeds on the floor.

The arched window, o'er whose pane
The bright sun shed his parting ray.
Reflects no more each crimson stain
And gorgeous tint of closing day.
The birds that built beneath the leaves.
Now flutter round those columns cold,
And night winds waft th' autumnal leaves
Over the crumbling pavement's mould.

There's scarce a murmur in the place,
From break of day till eventime ;
And human footsteps seldom trace
The path—the wild plants idly climb
Over the fallen roof, and hide
Half ruin's devastation there ;
Yet man, unthinking, turns aside
From that lone House of Prayer,

Year after year 'tis crumbling,
And heavily the loose stones fall
Long grass and fern hang clustering
Above the tombs without the wall.
Their name, their history, bath past;
But in these lonely graves recline
The mouldering. ashes of the last
Who worshipped at that shrine.

Oh, let the gaudy throng who read
• Some proud cathedral's lofty aisle,
Turn from each humble turf-clad bed
With haughty and contemptuous smile.
Dearer to me that silent glade,
Than lordly pomp and wealth's array—
More blest the yew's unbroken shade
Beside the ruins gray !

For hearts, now passionless, have stirred,
With love and faith long suffering, here ;
Man's pleading accents have hPen heard,
• And contrite woman's falling tear
Forgotten by the world they lie,
And still their dreamless slumber share,
Though storms o'ercast the summer's sky,
Above their House of Prayer'.

LECTURE ON OPTICS, MECHAN ICS' IMSTITUTION.

On Wednesday evening, Mr. Addams delivered the third
lecture of his course to a numerous and attentive audience.
It has been stated that when a ray of light comes into contact
with a body of denser medium than that through which it is
passing, it is refracted or bent from the direction it has been
pursuing. The question naturally arises, what occasions this
deflexion? It is owing to the difference in the density of the
nether in the new medium, which preverts the waves from tie-
Telling through it with the same rapidity as through the pre-
vious medium. BAs the same law, then, applies to refraction as
to reflection, tltat.fkoh.waves must pass through equal spaces,
and as the waves, when the rays are directed upon water in an
oblique direction, cannot all enter at the same moment, it
follows that those which have not entered will move more
rapidly than those which have, and that the length of these
waves will be shortened on reaching the water, and the body of
light assume a new direction. The atmospheric air refracts
the light which passes through it from the heavenly bodies,
hence the light of the sun is seen by us thirty-three minutes
after it has sunk below the horizon in consequence of its rays
being refracted in a circular manner, owing to the increasing
density in the atmosphere, as they descend to the earth's sur-
face. There are many advantages attending this property
of the atmosphere; by it our day is made longer than it other-
wise would be, and that without abstracting any light from the
inhabitants of another hemisphere. But there are many dis-
advantages. Persons taking astronomical observations must
make allowances fur this refraction. There are books publish-
ed for this purpose, containing tables of the refraction, according
to the degree of elevation, as the nearer the horizon the greater
the refraction, whilst in a vertical direction the rays of light
proceed at right angles, without any. refraction.
Light is totally reflected when it is passing from a dense me-
dium to a rarer one at a certain angle. Thus, if a ray-of light
be passing from water upwards towards the air so that it shall
describe an angle of 40 deg. and a few odd minutes, the ray
will be sent back as a tennis-ball from a wall. The reason of
this is, that, as the amount of refraction is greater than the
angle which is described above the water, the ray enters the
water in accordance with the law of refraction previously
given. A practical illustration of this may be readily afforded
by elevating .a common drinking glass at the angle of 40 deg.
between the light and the eye, when the rays will be rel.cted
_on the eye, and the under surface of the water will appear as
bright as any mirror. A person standing under the water will
see, upon looking up, the images of all external objects through
-au opening of 80 deg., whilst on every side of that space he
will see the images of the objects at the bottom of the water.
The angle varies in different substances, according to the
density of the either contained in them.
By means of a piece of glass of a certain curve, we may
bring all the rays of light to a certain point; and by a means
of a triangular bar of the same metal, called a prism, we can
refract light so as to make it available for certain purposes.
Flint glass possesses the highest refractive powers, on account
of the degree of lead it contains; plate glass has them in a
lesser degree, and crown glass least of all. Mr. Addams illus-
trated this by means of a prism, composed of three pieces, each
of different qualities of glass, and explained the method by
which the refractive powers of various substances were deter-
mined. Liquids are formed into prisms by enclosing them in
troughs of glass of different shapes.
Mr. Addams then described the various forms of glass used in
the formation of optical instruments, and their uses in refract-
ing light. Lenses may be made which will melt any known
substance with the utmost ease. Mr. Park constructed a burn-
ing glass three feet in diameter, by which he brought all the
light that was received upon its surface into a spot of one inch
in diameter. By means of another lens the rays were still
further concentrated into one-sixth of an inch. Supposing the
light of the sun to be 60 deg. and that all its rays were refracted,
'they would be concentrated into upwards of two millions of
times less space. With this instrument, Mr. Parke was en-
abled not only to melt iron and other substances, instantaneous-
ly,.but to dissipate them in smoke
Mr. Addams delivers his fourth lecture to-morrow evening.
In the report of the last lecture, it was erroneously stated
that blue and violet waves travel at a certain rate, instead of
generated in a certain number per second.