Babtista Porta, when he saw for the first time, on the walls of his dark chamber, the images of external nature, pictured by a sunbeam which found its way through only a small hole, little thought of the importance which would be attached to the instrument he was, from this cause, led to invent. The camera obscura of this Italian philosopher remained as a mere scientific toy for years, and it was not until Daguerre's discovery that its true value was estimated. It now plays a very important part in giving employment to at least ten thousand persons in this country alone.

It is of the utmost importance, in selecting a set of apparatus, to secure a good camera; for without such no one can obtain fine pictures. In testing it, see that it gives the pupil of the eye and lineaments of the features sharp and distinct; and that the whole image on the ground glass has a fine pearly hue. Look also to the field, and observe that the focus is good at the centre and extreme edges of the ground glass, at the same time. A poor camera generally gives a misty image, with the lights and shades apparently running together. The best American cameras are fully equal to those imported, while they cost much less; but there are great numbers sold which are not worth using.

If a lens gives a well defined image on the ground glass, it should do the same on the plate. Many a valuable lens has been condemned for failing in this, merely in consequence of the plate-holder not being in focus with the ground-glass. In case of deficiency in this, put a glass into the holder, lay a rule across the face, and measure the distance between them very exactly; measure the ground-glass in the same way, and make the distance agree perfectly, by moving the ground-glass either back or forward in the frame, as the case may be, so that the surface of the glass plate shall occupy precisely the same position as the face of the ground-glass when in the camera.

It is very desirable that the operator should understand the arrangement of the lenses in the tube; it not unfrequently happens, that in taking out the "glasses" to clean them, he does not return them to their proper places, and the result is that his "camera is spoiled." A couple of illustrations and a few remarks will be sufficient to enable any one to replace the lenses in them properly. Fig. 13 represents the tube for holding the lens, and Fig. 14 shows their arrangement. It will be seen that the two back lenses have a small space between them; this separation is kept by a small tube or ring of the same circumference as the lens. The two front lenses are nearest together. It will be observed that the two thick lenses are towards each other; these are made of flint glass containing much oxide of lead. The other two are double convex, and are made of crown glass. By noting the fact that the two cemented lenses go in the front of the tube, the glass having the thickest edge goes inside, and that the thickest lens of the other two goes in first, from the back of the tube, it will not be easy for the operator to make a mistake in returning the "glasses."

"I will remark that a diaphragm diminishes both chromatic and spherical aberration, by cutting off the outside portion of the lens. It lessens the brilliancy of the image, but improves the distinctness by preventing various rays from interfering with and confusing each other; it also causes a variety of objects at different distances to be in focus at the same time."

The tube containing the lenses is to be mounted on a box (camera-box) as in Fig. 15. For this purpose there are several patterns of boxes, from among which I have made two selections of the most approved, and represent them by cuts, Figs. 16, 17, 18.

Figs. 16 and 17 represent a bellows-box which is probably more in use than all the other patterns together. They serve both for copying and taking portraits from life. A is the base; B is the back and sliding-box; C, bellows, which admits of extension or contraction; D is the opening to receive the carriage A, Fig. 17; E is a thumb screw to hold the sliding-box at any required distance. Fig. 17 represents the plate-holder and ground glass frame.

A, carriage to pass through D, Fig. 16; B, frame for ground-glass, which may be turned in a horizontal or perpendicular position; C, a movable plate-holder held in place by means of springs; D, reducing holder, with bottom and plate to hold the glass plate: any size of reducing frame can be put in frame C; E E, spring bottom to keep frame D in place; F, slide; G, thumb-screw, when the carriage is to be put in or taken out of the box, Fig 16; H H, spring bottom to hold B in place.

Bellows-boxes can be obtained which receive the plate-holder from the top, the same as in the copying-box, Figs. 15 and 18. The common wood, or "copying-box," is represented by Fig. 18.

A, being the main or outside box, is made of wood veneered with rosewood; B is another box which fits into A, sliding in and out as required. The ground glass and plate-holders fit grooves made in the inside box.

In regard to plate-holders or tablets for holding the glass plates, it need only be said that the camera-boxes are accompanied with a complete set, so arranged that the light is wholly excluded from the plate while drawing out or pushing in the slide, for shutting off the light while the holder is out of the box. Should any one be desirous of using the same camera, for taking both glass and daguerreotype pictures, it will be necessary for him to be provided with two sets of tablets for his box, one for each process.

Camera Stands.

There are several patterns of these; almost every dealer has some particular style, which, if not for beauty, for his interest, suits his purposes best. Among the assortment, I will present only two illustrations. The first, Fig. 19, represents one which has an advantage over many others; it is made of cast iron, and of an ornamental pattern:—A, base on castors; B, fluted hollow column, which admits the iron tube C, which has on one side a hollow tooth rack to receive a spiral thread on the inner face of wheel D; this wheel, when turned, elevates or lowers the tube C to any desired height; E, thumb wheel attached to a screw which sets against tube C, to hold it in position, F, a pinion by which the camera can be directed; G G, thumb screws to hold the two plates together when in position. It is quite heavy, stands firm and solid, and is not liable to be moved by the jar from walking over the floor. For permanently located operators these are the most desirable; but for those who are moving about from place to place, and those who wish to take views, a lighter article would be more convenient, such as one represented at Fig. 20. This stand is made principally of wood, and can be readily taken apart, so as to be packed in an ordinary sized trunk.

Fig. 21 represents a small "Jenny Lind Stand," and is a very convenient article for the sitter to lean a hand or arm upon while sitting for a portrait; It is fixed with a rod for raising or lowering the top, and can be adjusted to any required height.

Head Rests.

There are several patterns of head supports, or, as they are commonly called, head rests, in use by the profession. I give two illustrations (Figs. 22 and 23). The first is an independent iron rest, known as the "Jenny Lind Rest;" and the other is for fastening to the back of a chair, as seen in the cut. For general use, I would recommend the iron independent rest as far more advisable than any other.

Vices for Holding Glass.

The article used for holding the glass, during the process of cleaning, is called a vice; and, of the numerous styles recently introduced, I find none that I would prefer to the old one known in market as "Peck's Vice;" it is simple and easy in operation, and at the same time is effectual. Fig. 24 represents this vice, which is to be firmly secured to a bench; the small piece of wood attached to the bottom is of no use. A A are the grooved for receiving the daguerreotype plate-block; but as they are too deep for the glass, I pin on a small strip of wood, so that the upper edge of the glass will be a little above the projection of the vice.

Nitrate Baths and Dipping Rods.

The accompanying illustration, Fig. 25, a, represents a bath for holding the nitrate of silver solution. This shape is of my own suggestion, and the best adapted to the wants of the photographer. It will be seen that the front side is rounding, with a curve extending from side to side. By this shape, the face of the glass is protected from coming in contact with the side of the bath—both edges of it turning so as to prevent injury. There is a small projection on the top, at the opposite side of the oval; this is to allow the solution to flow over and wash off any dust that may have gathered upon the surface of the solution. This wash runs out of a small tube, as is shown in the cut. Any convenient vessel can be placed under it to receive the liquid. This can be filtered and returned as often as required. I am not in the practice of filling my baths full of solution, but always keep them filtered and clean; hence saving an excess of solution.

b represents a little support, which is secured at its base Upon the shelf, to hold the bath in a slightly inclined position, which is preferable to having it stand perpendicularly.

Leveling Stands.

Persons oftentimes require a rest or place to put their glass during development or washing the picture. Either of the stands represented by the annexed cut will answer the purpose.

Fig. 30 is known to the daguerreotype operator as a "gilding stand," and is the one best adapted to the wants of operators on glass. It may be so arranged as to give the surface of the glass a water-level; D D are thumb-screws, by means of which, when properly regulated, the frame G may hold glass perfectly level and a large quantity of solution may be poured over the surface.

Printing Frames.

There are numerous methods and apparatus used for holding the negative and the paper during exposure to the light. The following illustrations represent a convenient and economical frame for this purpose.

Fig. 31 represents the front of the frame. The negative glass is held upon it by springs attached by screws to the bottom half of the frame, A, so that they can be turned on or off, to suit the different sizes of glass. On the other end of the spring are wooden buttons, which are placed on the edges of the glass negative, holding it in its place, and pressing it firmly against the paper which is placed under it. This frame is made of two pieces of inch board, which are connected by hinges, falling over as seen in Fig. 32, B being the half that is movable. This movable half is secured in position by means of a wooden button, attached to A on the back and under B, as seen in Fig. 32. The separate pieces, A and B, are bevelled where they connect, as seen by Fig. 31. D (in Fig. 32) is one of the springs, which can be seen in Fig. 31.

The entire bed or face of the frame, A and B, should be covered with a thick piece of satinet cloth, which may be pasted to the lower half, A, and extended over the entire surface of A and B. This forms a pad for the paper.

This printing frame can be easily made by any cabinet-maker or carpenter. The springs may be of sheet iron or brass—either will be found sufficiently stiff for the purpose. Every operator should be provided with from four to ten frames: the saving of time will be found to amply repay the expenditure necessary for a good supply.

Another article called a pressure frame, is represented in the accompanying figure. This is more expensive than the first, and is by some considered preferable.

Another cheap, convenient and equally good arrangement for holding the negative and paper, is to take three glasses—say one a full size, being the one having the negative upon it; and then take two glasses, each just half the size of the negative, and have a piece of very thick heavy cloth cut the size of the negative glass, which can be put between it and the two half glasses, and then they can be held together by means of the common spring clothes pin. The advantage of the two glasses at the back is, that one can be entirely removed while the picture is being examined, and afterwards returned without, in the least, moving the impression.

Collodion Vial.—Color-Boxes.

This shaped vial is made expressly for collodion, to which purpose it is admirably adapted. It has a wide mouth, and is so constructed that the liquid flows clear and free. It is deep, and with a heavy protruding base, to prevent its falling. There are two sizes made at present, one to contain 2½ ounces—the other, 1½ ounce. I generally use the smaller ones, but always keep on hand, and would not be without, a few of the larger size.

Fig. 35 represents a color-box. These can be had of any dealer, completely fitted, with color and brushes for use.