all light, with no shadows. She was thoroughly human. There

There is a style of French plates in the market, denominated heavy, which are truly excellent, if properly managed. Much patience, however, is required to remove the marks of the hammer; but with tripoli and alcohol the surface is readily cut down, and the plate is then susceptible of a beautiful black lustre by polishing with the buffer. The complaining operator could not succeed by his own method with one of the plates; he would encounter all manner of clouds and other unaccountable phenomena; he would imagine this plate entirely worn out before it was half cleaned, and soon fix in his own estimation the reputation of the heavy plate.

In making a choice of plates, therefore, it would appear to be a matter of perfect indifference with an experienced operator what kind he would use, except so far only as the labor required in cleaning them was to be taken into consideration.

The distinction between a scale plate, a Scovill No. 1, S. F., heavy A, star, crescent, eagle, or any other brand, consists in the superior finish of some, and the thinness of the silver in the cheaper qualities.

Consequently, let the complaining operator but employ the diligence inculcated in this article, to clean his plate thoroughly, so as to bring it to a perfectly even and level surface, and he will seldom be troubled with specks, clouds, dark patches, and the host of other obstacles which heretofore have tormented him.

AN ACCOUNT OF WOLCOTT AND JOHNSON'S EARLY EXPERIMENTS, IN THE DAGUERREOTYPE. BY JOHN JOHNSON.

[From Humphrey's Journal, vol. ii 185l]

As a general thing, however perfect any invention may be deemed by the inventor or discoverer, it falls to the lot of most, to be the subject of improvement and advancement, and especially is this the case with those new projects in science which open an untrodden field to the view of the artisan. Such has been, in an eminent degree, the case with the discovery first announced to the world by Mons. Jean Jaques Claude Daguerre, of Paris, in the year 1839, and which excited unbounded astonishment, curiosity and surprise. It may be questioned had any other than Daguerre himself discovered a like beautiful combination, whether the world would have been favored with details exhibiting so much care, patience and perseverance as the Daguerreotype on its introduction. Shortly after, these details reached the United States, by Professor S. F. B. Morse, of New York, who was, at the time of the discovery, residing in Paris. By this announcement, the whole scientific corps was set in operation, many repeating the experiments, following carefully the directions pointed out by Daguerre, as being necessary to success. Among the number in the United States, was Alexander S. Wolcott (since deceased) and myself; both of this city. On the morning of the 6th day of October, 1839, I took to A. Wolcott's residence, a full description of Daguerre's discovery, he being at the time engaged in the department of Mechanical Dentistry, on some work requiring his immediate attention, the work being promised at 2 P.M. that day; having, therefore, no opportunity to read the description for himself (a thing he was accustomed to do at all times, when investigating any subject). I read to him the paper, and proposed to him that if he would plan a camera (a matter he was fully acquainted with, both theoretically and practically), I would obtain the materials as specified by Daguerre. This being agreed to, I departed for the purpose, and on my return to his shop, he handed me the sketch of a camera box, without at all explaining in what manner the lens was to be mounted. This I also undertook to procure. After 2, P.M., he had more leisure, when he proceeded to complete the camera, introducing for that purpose a reflector in the back of the box, and also to affix a plate holder on the inside, with a slide to obtain the focus on the plate, prepared after the manner of Daguerre. While Mr. Wolcott was engaged with the camera, I busied myself in polishing the silver plate, or rather silver plated copper; but ere reaching the end preparatory to iodizing, I found I had nearly or quite removed the silver surface from off the plate, and that being the best piece of sliver-plated copper to be found, the first remedy at hand that suggested itself, was a burnisher, and a few strips were quickly burnished and polished. Meantime. the camera being finished, Mr. Wolcott, after reading for himself Daguerre's method of iodizing, prepared two plates, and placing them in the camera, guessed at the required time they should remain exposed to the action of the light; after mercurializing each in turn, and removing the iodized surface with a solution of common salt two successful impressions were obtained, each unlike the other! Considerable surprise was excited by this result, for each plate was managed precisely like the other. On referring to Daguerre, no explanation was found for this strange result; time, however, revealed to us that one picture was positive, and the other negative. On this subject I shall have much to say during the progress of the work. Investigating, the cause of this difference occupied the remainder of that day. However, another attempt was agreed upon, and the instruments, plates, etc., prepared and taken up into an attic room, in a position most favorable for light. Having duly arranged the camera, I sat for five minutes, and the result was a profile miniature (a miniature in reality,) or a plate not quite three-eighths of an inch square. Thus, with much deliberation and study, passed the first day in Daguerreotype-- little dreaming or knowing into what a labyrinth such a beginning was hastening us.

[Description of apparatus represented on pages 192 and 199:]