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you have for straightening out the fibres accomplish. They do that work.

[Exhibiting another preparation.]

That is the cotton hair and a portion of the seed. That is no photograph. It is the object itself. It is the cotton on the seed as it goes to the cotton-gin. It is torn off; and if a quantity of cotton can be taken from the bale and put under the microscope, it is found to be still twisted in that way. That is the ripe cotton.

I will take, now, a series of negatives. As I first showed the fibre, I don't think it best to take different pictures of that.

Here are photographs of Egyptian cotton. That which you see now illustrated upon the screen is just as the cotton lies together as it is taken from the bale. You can see that the fibres are tangled up. They lie crosswise in all kinds of positions; and yet each fibre has its particular twist.

Here is another exhibit of Egyptian cotton. Here again the cotton lies massed together.

Here, on this other side, is a preparation of Porto Rico cotton. If you will notice the fibre that comes in where I now indicate with the pointer, along in the centre between two others, you will see an illustration of what I mean by the twist of the cotton fibre itself while it is dry. If you will notice any one of these fibres, you will perceive that the appearance on the edge is different from that on the centre. That is due to the fibre being hollow and thicker at the edge than at the centre.

Here, on this other side, is an exhibit of some West India cotton of the Sea Island variety. The general appearance of these cottons is very much alike. The only difference will be in the more or less tangled condition of the fibre and in the size of the fibre itself.

Here, on another slide, which I now place in the instrument, we have some Venezuela cotton.

As an illustration of the resisting power of cellulose, or rather of the way in which it retains its mechanical arrangement after undergoing peculiar chemical changes, I will show you gun-cotton. This substance is made, you will recollect, by the replacing of three atoms of water with three atoms of nitric acid. The process of manufacture is by plunging the cotton in the acid and then washing and drying it. You would think that such a

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profound chemical change as that would make great changes in the microscopic appearance of the article as well. But you will see that, optically, its arrangement of fibres is substantially the same in the one whose image is now thrown upon the screen as in the one heretofore exhibited. There is no optical distinction between the two.

Here follow a series of three cottons. You have in the image pow thrown upon the screen, a specimen of what you call middling peeler" cotton, as it comes from the bale.

Mr. PALFREY. I should like to ask how many of those strands now shown on the screen would be found in a single fibre.

Dr. BOLLES. You can just see one, of those with the naked eye. When you separate cotton, and pull it out, each one of those is a thousandth of an inch in diameter.

Now, I will show you cotton after it has passed through what you call the railway head. This is not so good a photograph as some of the others; but, so far as this one specimen is concerned, you will perceive that the cotton does not present, as now projected on the screen, any appearance greatly different from that of cotton which had not been subjected to the action of the railway head.

Mr. CUMNOCK. Are those fibres put through a single or a double carding?

Dr. BOLLES. In this list of cottons, I have not the carding given as I had in some preparations which Mr. Bates gave me, and which in their examination would supply all the differences which practical gentlemen would like to know about.

We will now change our apparatus so that we can put on a high power of the microscope. In the first instance, I have a series of preparations mounted dry, which, by the kindness of Mr. Amory, I am permitted to use from the Nashua experiments ; and there you will be enabled to judge yourselves as to the changes which have been operative in the cotton. I will give you the marks as the manufacturer himself gave them in the series. With this half-inch lens, you will see everything magnified eight hundred diameters, and with the other, magnified one thousand diameters. The circle which you now see on the screen is at the lantern one-tenth of an inch in diameter.

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The first specimen is marked "Charleston cotton, just as it comes from the bale."

Those fibres are larger than you think, and they will bear close examination. I should like to have any gentleman who wishes to see just the structure of the cotton fibre, come close up to the screen and inspect it. With a lens that gives a full, field you cannot focus everything in the field at once. Now, you have the twist and the whole structure of each fibre. There has been no manipulation of the specimen. What you see is simply the image of the dry fibre projected upon the screen. I now exhibit it with a lens of higher power, magnifying one thousand diameters.

I will now replace that specimen with one marked " Mobile cotton, just as it comes from the bale.” My object in introducing these microscopical exhibitions of cotton fibres was to suggest the way in which you can study the question for yourselves. Of course it is a very delicate thing to exhibit these projections in a large room like this, and with such arrangements as I have been able to make here. But at your mills you can take preparations for the microscope of drawn yarn, or anything you please, and project the images and study them at your leisure on a large scale, and enjoy an admirable opportunity of comparison. There is still another method of illumination, which we will come to by and by.

I will take now a specimen which is marked " Charleston cotton.” There is no resource of optical science yet known that with these high powers, in projection, will give you a perfectly flat and perfectly distinct field. You have to take parts of it, and individual fibres. Perhaps Mr. Bicknell will try to find some of the ends of the fibres in the image now projected. One-tenth of an inch is the entire diameter of the circle on this slide. That would give for the image eight feet for the onetenth of an inch. What upon the slide would be one inch long, would give an image eighty feet in length. A fibre one inch long is magnified to a length of eighty feet.

Now, I wish to show you a series of these cottons as they were prepared, and I will give you the labels as they are on the slides. If the gentleman from Nashua is present, he would be the one to answer any question regarding the adjustment of the machinery through which the specimens had been passed. We

THE NEW YORK PUBLIC LIBRARY

ASTOR, LENOX AND TILDEN FOUNDATIONS.

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