the screen or curtain is then removed from the lens, and in a very few seconds the radiations from his person will, by their chemical action, produce an image or picture of him on the plate or paper. The picture thus obtained is at first invisible, and requires to be developed or exalted by the application of some chemical compound; and as it is also negative-the lights and shadows being reversed—an additional process is necessary to make it positive. But after these changes have been effected-and the lights and shadows fixed or rendered permanent by employing another chemical material-we obtain a portrait so exact and complete, that it will bear the most minute examination with a magnifying glass, the smallest details being depicted with perfect fidelity.

The great and beneficial influence which the sunbeam, by means of its three agencies of light, heat, and actinism, exerts on the phenomena of nature must be manifest to every observer. Vegetable organization is specially dependent on the influence of light. The etiolation of celery and sea-kale is familiar instances of the complete check which is put to the formation of colouring matter when light is obstructed; and in darkness every vegetable form passes rapidly into an unhealthy state. The germination of the seed is due to the chemical power of the sunbeam; the growth of the plant and the formation of wood to the luminous rays; and the process of flowering and the perfection of the fruit to the heat-rays. "Can you tell me what power is driving that train?" said George Stephenson to Dr Buckland, as, standing on the terrace at Drayton Manor, they observed a railway-train passing, and throwing behind it a long line of white steam. "Well," said the geologist, "I suppose it is one of your big engines."-" But what drives the engine?"-" Oh, very likely a canny Newcastle driver." -"What do you say to the light of the sun?" said Stephenson." How can that be?" asked the Doctor." It is nothing else," the engineer replied; "it is light absorbed thousands of years ago by plants during their growth, and bottled up in the carbon into which they were subsequently condensed; and now, after being buried in the earth for long

ages in fields of coal, that latent light is again brought forth, and made to work in the locomotive for great human purposes."

Compiled.

THE BUILDING OF THE SHIP.

"BUILD me straight, O worthy Master!
Staunch and strong, a goodly vessel,
That shall laugh at all disaster,

And with wave and whirlwind wrestle !"
The merchant's word

Delighted the Master heard ;

For his heart was in his work, and the heart
Giveth grace to every art:

And with a voice that was full of glee
He answered, "Erelong we will launch
A vessel as goodly, and strong, and staunch,
As ever weathered a wintry sea!"

And first, with nicest skill and art,
Perfect and finished in every part,

A little model the Master wrought,
Which should be to the larger plan
What the child is to the man,
Its counterpart in miniature;
That with a hand more swift and sure
The greater labour might be brought
To answer to the inward thought.
The model showed a gallant craft;

Broad in the beam-that the stress of the blast,
Pressing down upon sail and mast,

Might not the sharp bows overwhelm ;

Broad in the beam, but sloping aft
With graceful curve and slow degrees,
That she might be docile to the helm,
And that the currents of parted seas,
Closing behind with mighty force,
Might aid and not impede her course.

Covering many a rood of ground,
Lay the timber piled around;

Timber of chestnut, and elm, and oak,

And, scattered here and there, with these,
The knarred and crooked cedar knees;
Brought from regions far away,
From Pascagoula's sunny bay,

And the banks of the roaring Roanoke! Ah! what a wondrous thing it is

To note how many wheels of toil One thought, one word, can set in motion ! There's not a ship that sails the ocean, But every climate, every soil, Must bring its tribute great or small, And help to build the wooden wall!

With the next rising of the sun

Was the noble task begun;

And soon throughout the shipyard's bounds

Were heard the intermingled sounds

Of axes, and of mallets, plied

With vigorous arms on every side;
Plied so deftly and so well,

That, ere the shadows of evening fell,
The keel of oak for a noble ship,
Scarfed and bolted, straight and strong,
Was lying ready, and stretched along

The blocks, well placed upon the slip.

Day by day the vessel grew,
With timbers fashioned strong and true,
Stemson and keelson and sternson knee,
Till framed with perfect symmetry,
A skeleton ship rose up to view!
And around the bows and along the side
The heavy hammers and mallets plied,
Till after many a week, at length,
Wonderful for form and strength,
Sublime in its enormous bulk,
Loomed aloft the shadowy hulk!

With oaken brace and copper band
Lay the rudder on the sand,

That, like a thought, should have control
Over the movement of the whole;

And near it the anchor, whose giant hand
Would reach down and grapple the land,

And immovable and fast

Hold the great ship against the bellowing blast!
And at the bows an image stood,
By a cunning artist carved in wood,
With robes of white, that far behind
Seemed to be fluttering in the wind,
It was not shaped in a classic mould-
Not like a Nymph or Goddess of old,
Or Naiad rising from the water—
But modelled from the Master's daughter!
On many a dreary and misty night,

"Twill be seen by the rays of the signal light, Speeding along through the rain and the dark, Like a ghost in its snow-white sark!

May remind them for evermore

Of their native forests they shall not see again.

All is finished! and to-day

The gallant vessel shall be launched!--
With fleecy clouds the sky is blanched,
And o'er the bay,

Slowly, in all its splendours dight,
The great sun rises to behold the sight.

The ocean old,

Strong as youth, and as uncontrolled,

Paces restless to and fro,

Up and down the sands of gold:

His beating heart is not at rest;
And far and wide,

With ceaseless flow,

His beard of snow

Heaves with the heaving of his breast.
He waits impatient for his bride :

And there she stands,

With her foot upon the sands,

Decked with flags and streamers gay,

In honour of her marriage-day!

Then the Master, with a gesture of command,

Waves his hand;

And at the word,

Loud and sudden there is heard,

All around her and below,

The sound of hammers, blow on blow,

Knocking away the shores and spurs.
And see! she stirs !

She starts, she moves,-she seems to feel
The thrill of life along her keel,—

And, spurning with her foot the ground,
With one exulting, joyous bound,

She leaps into the ocean's arms!
And hark from the assembled crowd
Rises a shout, prolonged and loud,
That to the ocean seems to say,—
"Take her, O bridegroom, old and gray,
Take her to thy protecting arms,
With all her youth and all her charms!"

Sail forth into the sea, O ship!

Through wind and wave right onward steer!

The moistened eye, the trembling lip,

Are not the signs of doubt or fear!

Sail on, nor dread to breast the sea!

Our hearts, our hopes are all with thee;

Our hearts, our hopes, our prayers, our tears,

Our faith triumphant o'er our fears,

Are all with thee,—are all with thee!

LONGFELLOW.