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what is the use of the membrane, which is stretched over the tube of which you told us?
Mamma. It is a very proper question ; its porpose is to convey the vibrations of the air, which are received through the outer ear, to the chain of bones in the tympanum.
Frank. Is it stretched straight across them like the parchment on the head of a drum?
Mamma. No, it is on the contrary funnel shaped, that is, drawn down in the centre from the weight of one of the four bones which adhere to it.
Jane. Is the membrane thick and tough?
Mamma. No it is transparent; but yet, like all the other membranes in the body, it is furnished with a great quantity of vessels.
Emily. You were going to tell us about the little bones in the tympanum, when I interrupted you, mamma.
Mamma. . Yes, there are four of these very curious little bones in each ear; and they are so constructed as to transmit to the foramen ovale, the vibrations of the air, which are received on the membrane of the tympanum. They are articulated with each other, and fastened by ligaments, so as to form a complete chain.
Jane. I guess they have got some muscles too, that they may be able to move about.
Mamma. You are right, Jane; and they are so formed, as not only to transmit the vibrations they receive, but also to increase their force; whilst the small muscles I have just named, enable them to adapt the tension of the membrane to the strength of the impulse-and thus they both guard the ear against too violent shocks, and increase its power to hear weak sounds.
Emily. How very wonderful!
Frank. Have those four bones particular names mamma?
Mamma. Yes; and they are given to them because they are supposed to resemble the objects whose name they bear. The first is the malleus.
Frank. That is Latin for a Hammer or mallet, is it not, mamma?
Mamma. Yes; and the shape of this little bone is like a hammer. Its form resembles the bone of the thigh. The body of it, which is like the handle of the hammer, is joined to the membrane of the tympanum. It is not equally thick all over the handle part, but has projections towards the head.
Emily. What is the name of the second bone, mamma?
Mamma. The incus-wbich means-what?
Mamma. Yes; but this bone in reality is more like a large double tooth, with a hollow in the centre, into which the malleus or hammer, strikes or falls. The shorter leg, and the body of the bone, lie on the margin of the circular opening of the tympanum. The long leg hangs down into the tympanum, and is joined at its point to the third bone, which is called the os orbiculare.
Frank. That means a round bone, does it not?
Mamma. Yes. This is the most curious, because the smallest bone in the body,-it is not larger than a grain of sand, and yet without it was in its place, the whole chain would be imperfect. But there is yet another bone to complete the series, this is called the stapes, which means-what?
Frank. A stirrup, mamma?
Mamma. Yes; and it is really very much like one in shape-only it is elegantly grooved within.
Emily. And has it a hole at the bottom like a stirrup?
Mamma. No; but its base is flat on one side, in order that it may be fitted to the foramen ovale, as it is fastened to the membrane, which is stretched over it.
Jane. I am sure you were right, mamma, in saying, that the ear is not so simple a thing as I was foolish enough to imagine.
Frank. But mamma has not yet described to us the labyrinth, which is the most intricate part of all.
Mamma. True, my dear; but I must first tell you, that the little chain of bones with wbich you are now acquainted, is so wonderfully made, that each one performs the exact office required in order to convey sound to the nerve, through which the sensation of hearing is communicated to the brain. Repeat to me the names of the four bones.
Frank. First, the malleus, or hammer.
[To be Continued.)
TO THE EDITOR OF THE CHRISTIAN
MADAM, As a constant and diligent reader of your periodical, may I be permitted to suggest a trifling extension of the space allotted to notices of books. There are many families, particularly in places remote from the British metropolis, who are indebted to your Magazine for the introduction of suitable books, which they would not otherwise have heard of. Now could you not spare an additional page or two, just to give us the titles works that you have read, and can conscientiously recommend ? I believe that by so doing you would oblige and serve three parties—authors, publishers, and readers. There are also little books for little people, which, howsoever the dignity of regular criticism may overlook them, we, who have the care of selecting a nursery library, are very glad to hear something of. You have put us on our guard against the writings of a certain school: and I speak the wishes of many mothers, when I ask you occasionally to point out, not only what we should shun, but what we may safely adopt,
[We are obliged for this suggestion-it has been made from other quarters also; and our friends will perceive that we commence acting upon it in the present number.---EDITOR.]
Review of Books.
MEMORIALS OF THE SEA. By the Rev. Wm.
Scoresby, B. D. Incumbent of Bedford Episcopal Chapel, Exeter, Fellow of the Royal Societies of London and Edinburgh ; corresponding member of the Institute of France ; &c. Nisbet.
The primary design of our pious author is to demonstrate the peculiar blessing attending a resolute observance of the Sabbath, under circumstances fraught with strong temptation to set aside the divine ordinance. Mr. Scoresby is well known, as a faithful minister of the gospel, whose writings, on various occasions, are already before the public. He was formerly in command of a vessel employed in the whale fishery, and his recitals of the providential success which crowned, on other days, the efforts that were invariably intermitted on the hallowed day of rest, are exceedingly encouraging. We do not know whether the book can possess so strong an interest for readers who have never gone down to the sea in ships, and beheld God's wonders in the deep, as we have been privileged to do; but to every class it is calculated to be really useful and profitable, to mariners, eminently so.