TECHNOLOGICAL & MICROSCOPIC REPOSITORY; OR, DISCOVERIES AND IMPROVEMENTS IN THE Useful Arts, BEING A CONTINUATION OF HIS TECHNICAL REPOSITORY. BY THOMAS GILL, Patent-Agent, AND DEMONSTRATOR IN TECHNOLOGY, ON THE APPLICATION OF SCIENCE TO THE USEFUL ARTS AND MANUFACTURES; UPWARDS OF TWENTY YEARS A CHAIRMAN OF THE COMMITTEE OF MECHANICS IN THE SOCIETY FOR THE ENCOURAGEMENT OF ARTS, MANUFACTURES, AND COMMERCE, ADELPHI, LONDON; HONORARY MEMBER OF THE ROYAL PRUSSIAN ECONOMICAL SOCIETY OF POTSDAM; AND A CORRESPONDING MEMBER OF THE ROYAL BAVARIAN POLYTECHNICAL AND AGRICULTURAL SOCIETIES OF MUNICH. VOL. VI. LONDON: PRINTED BY W. SPIERS, 399, OXFORD-STREET; EDITED AT GILL'S PATENT AGENCY & COMMISSION OFFICE, PUBLISHED BY THOMAS HURST, EDWARD CHANCE, AND COMPANY, 65, ST. PAUL'S CHURCH-YARD; AND SOLD BY THE FOLLOWING OPTICIANS, viz: CAREY, STRAND; BANCKS, BOND STREET; WATKINS and HILL, CHARING CROSS; ALSO BY THE FOLLOWING BOOKSELLERS, viz: LONGMAN and co. and BALDWIN and co. PATERNOSTER ROW; W. SPIERS, oxford STREET; LIMBIRD, STRAND; and GRIFFITHS, wellington STREET, LIKEWISE BY TRUETTEL and WURTZ, PARIS and STRASBURG: and DOBSON, PHILADELPHIA : LONDON: AND BY OTHER PRINCIPAL OPTICIANS, BOOKSELLERS AND NEWSMEN IN TOWN & COUNTRY. 1830. GILL'S TECHNOLOGICAL & MICROSCOPIC REPOSITORY. I.-On the Microscope. By THOMAS CARPENTER, Esq. With Remarks and Additions. By the EDITOR, WITH A PLATE. DEAR SIR, London, December 8th, 1829. I FEEL great pleasure in complying with your request, of sending for your examination a few microscopic objects, from the collection in my possession. Within the ten talc sliders you will find the following objects, which, I trust, will afford you much gratification, in tracing out, under your microscope, the numerous and diversified characters with which they are adorned, the beauties of which escape the unassisted sight. The antennæ of various insects afford numerous interesting objects, as a sample of which, I send some from the curculio, carabus, cimex, and the midge-fly, which latter insect is so exceedingly minute, as to be nearly invisible to the eye, and yet it contains most exquisite workmanship. There is also, in the same slider, a few seeds and seedvessels from a fern. The various parts of fern will furnish you with many objects. many objects. I have sent you a few small portions of the leaves, on the under side of which you will perceive numerous clusters of seeds, covered over with a fine skin or membrane, full of pores or air-vessels for the purpose of admitting air to the pods containing the seeds, some of these skins are within the talc slider just mentioned. These pods appear to the naked eye to be the seeds, instead of which, each pod, small as it is, contains numerous seeds, which, by the assistance of the microscope, may be distinctly seen. VOL. VI. The minuteness of these seeds is astonishing. These may be distinctly seen on some pieces of card, on which I have placed some pods, which, bursting, have discharged their contents on the surface of the card. On a piece of the fern leaf, is also the cast skin of an aphis, covered over with seeds by the bursting of the pods. In the selection from the leaves, I have sent specimens of the seeds in their various stages towards ripeness, and in which you will find much to admire. I have also enclosed, between slips of glass, numerous seeds, and seed-cases from the same plant, to be viewed as transparent objects; also a few of the smaller leaves, in which you will perceive very fine reticulations, together with a few transverse sections, cut from the roots and branches of the plants. These are very beautifully marked, and form grand objects indeed, for the lucernal or solar microscopes. In the talc sliders before mentioned, are also dissections from various parts of the sheep tick, the rostrum of the cimex lectularius, scales from a butterfly, hairs from the cast skin of a species of dermestes. The lower lip and palpi of the cock-roach, some curious scales taken from the feelers of a small hunting spider, hair from a field-mouse, also some hair from a rat, with the eggs of the louse which infests that animal adhering to the hair, minute scales from some of the smaller moths, various ticks taken from pigeons, the insect described in Adams on the microscope, as the lobster insect, the proboscis of a flea displayed, a very minute acarus, that is frequently found running very nimbly over the leaves and fruit of the currant tree, various cast skins from the aphides, eggs from the flea of the cat, among which are also seen some of the caterpillars in the act of coming forth, and others quite out, leaving the empty shells, as curious transparent objects. Within the last talc slider, No. 12, there is the cast skin of a cimex, farina of the major convolvulus, farina of the holly-oak, antennæ of a gnat, parts of the tympanums or drums of a fly, which are situated under the wings of the insect. The down attached to the various species of the thistle, affords fine objects for the microscope; these you will have frequent opportunities of collecting. I send you a curious specimen of one of the foreign seeds, with the down attached to it; in appearance it resembles a shuttlecock. Some of this down I have also placed between slips of glass, and which forms an excellent object. I also send you the wing-cases of a cimex, placed between talc in a box slider. And, between slips of glass, there are wingcases of other species of cimices, together with the head and proboscis of one species dissected. The genus cimex affords an abundant field, from which you may derive most splendid objects for your microscope; the workmanship or characters displayed in some of the wing-cases, are highly interesting. Between these glasses are likewise some specimens of farina from various flowers, sent you, in order that you may examine them as opaque objects, by placing a piece of black card behind them; which method I think you will prefer to viewing them as transparent objects, as you will then have the advantage of seeing the colour of the farina as well as the characters, in viewing them as opaque objects. Between another slip of glass I have enclosed four wingcases of one of the common cicadas. Many other wingcases of this genus are also elegant microscopic objects. The fucus or sea-weed, affords numerous fine objects, a few specimens of which I have also placed between glass slips. These I received from Brighton, and when exhibited under the lucernal or solar microscope, they will produce a fine effect. Amongst the various objects herein enumerated, there are some whose characters are very difficult to define; but, as I before-mentioned, I have the loan of an excellent achromatic object-glass from my friend Mr. W. Tulley, so I shall feel happy in placing them before it, in order that you may observe the interesting characters contained within them. With the foregoing, I also send you two or three species of our common cicada, usually termed frog-hoppers, from some fancied resemblance to the colour and shape of that |