Mr. Jones has found that a large square glass, from twelve to sixteen inches in the side, rough ground on one of its surfaces, exhibits the objects the best of any other contrivance; answers tolerably well for opake objects, and gives the artist the means of tracing their figure most correctly on its surface. Such sort of objects he fixes upon slips of glass for that purpose, or applies them to a pair of nippers shewn at _b_, sent with the microscope. A concave silver speculum screws on at _c_, before the magnifiers, which reflects upon the objects the light that issues from the lamp through the body of the microscope. The least dimensions of the lanthorn are about ten inches square, and fourteen inches high. This microscope and lanthorn, when made as a separate apparatus from the lucernal, is called the LANTHORN MICROSCOPE. Its effect is considerably short of what is produced by the solar microscope, and not equal to what is much wished for in this manner of magnifying minute objects; see note, page 77. Partly from the improvements just described, Mr. Jones is now constructing a lucernal microscope that he conceives will be the most simple and perfect yet made. It could not be completed in time to be described in this work; but its improvement and advantages will be quite evident to any reader who has attended to the description which I have just given. DESCRIPTION OF CUFF’S DOUBLE-CONSTRUCTED MICROSCOPE, REPRESENTED AT Fig. 1. Plate VII. A.[32] [32] The compound or double microscope is in more general use than any other sort. Besides its being less expensive than the lucernal or complete solar, it is found commodious and portable in the observer’s apartment, when only a confined degree of microscopical pursuit is intended, and that chiefly for a few hours amusement; it may be used both by day and night. In the most improved of this kind the objects appear magnified in a field of view from about 12 to 15 inches in diameter. It is better adapted to transparent than to opake objects, yet the latter may often be viewed to great advantage by the assistance of the sun’s rays or the light of a candle condensed on them. The intelligent reader, by attending to the accounts of the different microscopes described in this work, will be enabled to select that best adapted to the kind of objects he wishes to explore, and the manner in which he is desirous of having them exhibited. EDIT. This instrument was first described by Mr. Baker, and recommended by him. It was also described by my father in the fourth edition of his Micrographia Illustrata, page xix. A B C represents the body of this microscope; it contains an eye-glass at A, a large lens at B, and a magnifier which is screwed on at C, one of which is represented at Q. The body of the microscope is supported by the arm D E, from which it may be removed at pleasure.