TWO CLASSES OF SUBSTANCES.

5

We have, in this little cabinet, a number of specimens, sufficient to engage our attention for a great many evenings; but I shall only speak of one of them to-night. We must, however, pursue some kind of method. I will therefore begin by observing, that all the substances contained in this cabinet, indeed every substance with which we are acquainted, may be divided into two classes. They are natural or artificial bodies.

By a natural body, I mean something which was made such as we see it by the power and wisdom of God.-An artificial body became what it is by the art and contrivance of man.

Here is a piece of glass; do you call it a natural or an artificial substance? Take it into your hands, and examine it;-what qualities can you discover by the sense of feeling?

It is hard, smooth, and cold.

And what can the eye observe?

The surface is bright, as well as smooth. There is also another property of which the eye can judge the peculiar property which makes glass so useful: I think I need not tell

6

PROPERTIES OF GLASS.

you what it is.

But can you tell me the word by which people usually express this property, this clearness of substance, which enables you to see through the glass, to discern objects beyond it, as if the glass were not there?

We say, glass is transparent; but perhaps you do not thoroughly understand why the word transparent is so very expressive of this clearness; it is borrowed from the Latin, and has no meaning to English ears till the sense of it is explained trans means beyond, on the other side; and parent is taken from another Latin word, which means to appear; so that a substance is transparent when objects appear on the other side of it; that is, when we can look through the substance.

If I wet my finger, and pass it round and round the edge of this tumbler, which is partly filled with water, you will be sensible of another property in glass-you now hear a musical tone: those who attended Mr. Addams' Lectures, and saw him draw the bow of a violin over the edge of several glass vessels, heard a very pleas

TERMS EXPLAINED.

7

ing variety of musical tones. Substances which can be made to produce loud and shrill sounds are called sonorous bodies.

norous.

Glass, then, has properties which are evident to three of our senses.-Touch discovers that it is hard, smooth, and cold: Sight, that it is bright and transparent: Hearing, that it is soTaste discovers nothing, therefore we call it insipid. Smell discovers nothing, therefore we say that glass is inodorous. The syllable in is also borrowed from the Latin, it expresses the absence of a quality :-insipid, without taste; inodorous, without smell.

Now that we have examined such qualities of glass as are obvious to our senses, and determined that it belongs to the class of artificial substances, (i. e. those which have been brought into their present form by the art of man,) perhaps you may like to know how he came to find out the way of making it. And here we must observe a great distinction between the works of man and the works of God. There is only one Crea

tor.

Every thing we see, whether it be what is

8

MAHOGANY-TREE.

called a natural substance or an artificial one, owes its origin, its first state, to the power and wisdom of the one great Creator.

This little cabinet before us is an artificial body, it was made by the art of man; but he used for the purpose part of a mahogany-tree, which probably came from one of the West Indian islands; or the countries on the Western shores of the Gulf of Mexico: this piece of wood, then, was part of a graceful tree with many branches, smooth, shining leaves, something like those of a laurel, and bunches of small, whitish flowers. I need not tell you whose power made the mahogany-tree, but I wish to impress upon you the vast, immeasureable distance between man, who can only shape and mix together the substances that he finds already made, and the Great Almighty Being who creates these substances, and gives man sense to make use of them. The one subsists by Himself; He has need of nothing: the other, for every thing he uses, for his life, and for what he calls his own cleverness, is indebted to God.

PLINY'S ACCOUNT.

9

Man is also indebted to his Creator in another way, which he is very apt to overlook or forget. God governs the world by his providence. He knows every thing that happens, and appoints or directs events for the benefit of his creatures. Many very useful discoveries have arisen from circumstances which were quite unexpected, which man could not have contrived; therefore he should be thankful when such circumstances happen, and not take all the merit to his own cleverness.

In two of the entertaining Lectures we have lately heard, allusion was made to the accident, or unforeseen circumstance, which is supposed to have led to the discovery of glass. The story is this: Pliny (the same Pliny who was so remarkable for his love of natural history, and whose eager curiosity to observe the effects of that eruption of Vesuvius, which destroyed the city of Herculaneum, cost him his life) relates, that some merchants, being overtaken by a storm, were driven into the mouth of the river Belus, in Syria. Whether they were shipwrecked