Interesting Correspondence from China.

Messrs. Editors:--Your paper seems to increase in interest. I brought the back volumes from Madras to Pekin, and am glad to refer to them here where I must depend upon myself.

I have been building and repairing premises since I came here last year.

I find the carpenters and masons are very much delighted with our tools, especially our saws, planes, borers, vise, and hammers. Our lathe is a wonder. They use only the ancient spindle turned backwards and forwards by a treadle or by the left hand while the right guides the chisel or turning-tool, which cuts only half the time. They use only the turning saw, which often fails them because it cannot be used in splitting wide boards in the middle, and in many other places. They are great sawyers, however. They stand heavy pine spars on end, if rather short, say 8 feet, the common length of many intended for making coffins, and cut them up into three-eighths or half-inch stuff with great patience. A longer one they will lean over and prop up, raising it towards the perpendicular as they advance. They must have some hard jobs. I have just measured a poplar plank in front of a coffin manufactory, which I found to be 5 ft. 3 in. at the b.u.t.t, 3 ft. 10 in. at the top, 8 feet long, and about 8 inches thick. For a crosscut saw they rig one like our wood-saw. I am sure it would deeply interest you to make a visit to Pekin and see how this ancient, patient, and industrious people do their work. It is truly painful to see how much time they spend in making the simplest tool for want of at least a few labor-saving appliances.

Doubtless you have their tools on show in New York. They are to me an interesting study, though I have been long familiar with the rude tools of the Hindoos. It is constantly suggested to me that we must have got many hints from the Chinese, or else indeed they have taken hints from the West; or again, which is perhaps the true solution, implements like words have a common origin. I should think from what I have observed in a short time, that the Chinese resemble the Europeans in their tools more than the Hindoos--a thing I did not at all antic.i.p.ate. A clever man could write you an interesting chapter on the ways of the Pekinese, the Chinese Manchus, Mongols, and the rest mixed together, though the Chinese are confessedly the workers in wood, iron, and everything else.

The Manchus are mostly hangers on of the government, living mainly upon a miserable monthly stipend.

The reading of your unequaled journal makes me interested in you as if you were personal friends, and so I have run away with these pointless remarks. I am sure you will excuse me, and not wonder that one wishes to breathe now and then.

I was an old subscriber in Madras, and hope to be till I can read no longer. My son, who perished at Andersonville, was a subscriber to the SCIENTIFIC AMERICAN till the day of his capture by Mosby.

Pekin, China.

P.R. Hunt.

Communication Between Deaf and Blind Mutes.

Messrs. Editors:--In a recent number of the SCIENTIFIC AMERICAN I notice an ingenious method of teaching deaf and dumb persons to converse in the dark, which is also applicable to blind mutes, and it brings to my recollection a method which was in use among the "telegraph boys" some years ago when I was one of them. Sometimes when we were visiting and asked to communicate to a "brother chip," anything that it was not advisable for the persons around us to know, a slight tap-tapping on the table or chair would draw the attention of the party we asked to talk to, and then by his watching the forefinger of the writer, if across the room, or if near enough, by placing the hand of the writer carelessly on the shoulder of the party we desired to communicate with, the communication was written out in the telegraph alphabet or by taking hold of his hand and writing upon the finger.

I think this method will be found much less complicated, if not quite as rapid, as the method with both hands, and much more convenient, as it is only necessary to have hold of one hand of the person communicated with, and is more rapid than writing with a pen.

For the benefit of those not acquainted with the telegraph alphabet, I give it:

A B C D E F G H I .- -... ... -.. . .-. --. .... ..

J K L M N O P Q -.-. -.- --- -- -. . . ..... ..-.

R S T U V W X Y . .. ... - ..- ...- .-- ..-. .. ..

Z ... .

The uninitiated will observe that O differs from I in the distance between the dots, made thus: I by two quick strokes of the forefinger; O by one quick stroke, slight pause, and another quick stroke; the dashes are made by holding the finger down for a short s.p.a.ce: thus SCIENTIFIC AMERICAN would be written:

S C I E N T I F I C ... .. . .. . -. - .. .-. .. .. .

A M E R I C A N .- -- . . .. .. .. . .- -.

In a very short time any one can learn to read by the sight or by the touch. Anything which can add to the pleasure or comfort of these unfortunates is of importance.

MAGNET

[Nothing can compensate for want of rapidity in a language designed for colloquy. Although our correspondent found the Morse telegraph alphabet a resource on occasion, he would scarcely be content to use it, and it only for life, even if emanc.i.p.ation from it involved months of labor.

The motions required to spell SCIENTIFIC AMERICAN by the telegraph alphabet are thirty-nine, but as the short dashes occupy the time of two dots for each dash, and there are eight of these, eight more ought to be counted in a comparison of it with an alphabet composed wholly of dots, this would make forty-seven. To spell the same words in full by the mute alphabet referred to would require only twenty-three motions. A still greater disparity in rate would, we think, be found in an entire colloquial sentence. Thus the sentence "Hand me an apple" would require, by the mute alphabet, the time of fourteen dots, while with the telegraph alphabet it would require the time of thirty-nine.--Eds.]

Cheap Cotton Press Wanted.

Messrs. Munn & Co.:--Please give us any information of cheap cotton-presses, such as small neighborhoods, or single planters, in the South could own. In particular, a press that will put 40 pounds cotton into each cubic foot. We want cotton better handled, and to that end may want small bales, say 150 pounds each. But these must be put into three or four cubic feet, or they will cost too much for covering, ties, etc.

Perhaps you can furnish us with a wood-cut of some, or several, presses worked by hand, or by horse-power, that will do good service, not cost too much, be simple in operation, not require too much power, and be effective as above. It may be for the interest of some of your clients or correspondents to give us the facts, as we shall put them into a report for circulation amongst the entire cotton interest of the country.

Yours very truly,

WALTER WELLS, _Sec'y_.

National a.s.sociation of Cotton Manufacturers and Planters, No. 11, Pemberton Square, Boston, Ma.s.s.

A Singular Freak of a Magnet.

Messrs. Editors:--In my library hangs a powerful horseshoe magnet which has a keeper and a weight attached of about three ounces. This weight is sustained firmly by the attracting power of the magnet, and is not easily shaken off by any oscillating motion, yet through some (to me) unknown cause during each of the last ten nights the magnet has lost its power, and the keeper and weight lie in the morning on the bottom of the case where the magnet has hung for many years without a like occurrence, except once on the occasion of a severe shock of an earthquake which took place December 17, 1867.

There is no possible way for this magnet to be disturbed except by the electric current; then why should its power thus return without the aid of a battery or keeper? Will some one explain?

FLOYD HAMBLIN.

Madrid Springs, N.Y.

Speaking makes the ready man, writing the correct man, and reading the full man.

PRESERVATION OF IRON.

BY PROF. HENRY E. COLTON.