There are several different forms of pocket lenses, but for general work there is, perhaps, nothing more convenient and serviceable than the ‘triplet’ magnifier. It is a combination of three lenses, enclosed in a pocket case, and so arranged that they may be used separately or in combination, thus supplying a variety of powers. The three lenses of the triplet are themselves of different magnifying powers, and these powers may be increased by combining two or all of them. For work at home a ‘dissecting microscope’ is very useful. This consists of a magnifying lens, mounted on a support over a surface on which small objects may be examined and dissected, the height of the lens being, of course, adjusted according to its focal distance. Lenses ready mounted on adjustable stands may be purchased for this purpose, but no one ought to experience much difficulty in designing and constructing some simple stand that will give every satisfaction. The arrangement just described is, of course, suitable for the dissection of only small objects, and these are placed on a material adapted to the nature of the work to be done. Thus it is sometimes convenient to place the object to be examined on a small sheet of cork, in order that it may be secured by means of pins while the dissection proceeds, while at other times it is essential that it be laid on a hard and unyielding surface, such as that of a slip of glass. But whatever be the nature of the substance on which the dissection is made, its colour may be regulated according to that of the object. If, for example, we are dissecting a small white flower on a piece of cork, we should naturally blacken the cork, or cover it with a piece of dead black paper; or, if we are to dissect a small, light-coloured object on a glass surface, we lay the glass on black paper. [Illustration: FIG. 45--THE TRIPLET MAGNIFIER] The advantage of dissecting objects under water does not seem to be generally appreciated by beginners, who often allow their specimens to become dry and shrivelled, almost beyond recognition, during the progress of their examination. This mode of dissection is certainly not necessary with all objects, but may be generally recommended for soft and succulent vegetable structures, as well as for almost all animal dissections. This being the case, arrangements should certainly be made to provide a miniature dissecting trough as an accessory to the dissecting microscope, and the following instructions will enable the reader to construct a highly satisfactory and inexpensive one:--