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IN order to examine objects by the Solar Microscope, the room is made completely dark, and the sun's light being transmitted by the looking-glass AB through the lens E in a horizontal direction, the appearance of the object is thrown upon a white screen, or sheet, prodigiously magnified. In the fig

ure CD is a circular plate which turns round by means of the button F, and by means of the buttom G the looking glass is elevated or depressed, so that by these motions the light is regulated. The object is placed in an ivory slider through a hole near H, the end of the tube.

An accurate account of the magnifying power of each magnifier, as exhibited on the

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Human blood, and the blood of land animals, is found, by the microscope, to consist of round red globules, floating in a transpar

ent water, or serum: the specific gravity of these globules is somewhat more than the serum wherein they float.

In order to view the circulation of the blood by the microscope, we must use such small creatures as, by their transparency, will permit us to see through them.

The transparent membrane between the toes of a frog's hind foot, is an object very convenient for viewing the current and circulation of the blood; and in this, if well expanded, it may be seen fairly and distinctly, flowing through innumerable veins and arteries, like the rivers in a map.

In the fins and tails of fish, it may likewise be observed: but here, the streams flow nearly in parallel lines, in the direction of the bones.

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In Tadpoles, (commonly called toad fish,) the circulation can be seen in a very pleasing manner; the globules changing their form, and growing less in diameter, so as to pass through smaller veins.

The Moscheto Insect.

The Moscheto, or gnat insect, in its middle state, between a maggot and a moscheto, may be found abundantly in rain water. It makes an astonishing appearance when magnified on the screen to the length of six or eight feet, when the bulk is magnified more than five hundred and seventy millions of times. The pulse may be visibly seen to beat, in the dark central part, which appears to be two great veins, or blood vessels, as they sometimes separate, so that light may be seen between them. In the head,

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