TECHNOLOGICAL 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 UPWARDS OF TWENTY YEARS A CHAIRMAN OF THE COMMITTEE OF MECHANICS IN THE AND COMMERCE, ADELPHI, LONDON; HONORARY MEMBER OF THE ROYAL PRUSSIAN ECONOMICAL SOCIETY OF POTSDAM; AND AND AGRICULTURAL SOCIETIES OF MUNICH. VOL. V. LONDON: PRINTED BY W. SPIERS, EDITED AT GILL'S PATENT AGENCY & COMMISSION OFFICE, 125, STRAND, NEAR TO SAVOY AND WELLINGTON STREETS; PUBLISHED BY THOMAS HURST, EDWARD CHANCE, AND COMPANY, AND SOLD BY THE FOLLOWING OPTICIANS, viz:- CAREY, STRAND; BANCKS, STRAND; WATKINS and HILL, CHARING CROSS; P. CARPENTER, REGENT STREET; WEST, FLEET STREET; ALSO BY THE FOLLOWING BOOKSELLERS, viz:- LONGMAN and co. and BALDWIN and Co. PATERNOSTER ROW; W. SPIERS, OXFORD LIKEWISE BY TRUETTFL and WURTZ, PARIS and STRASBURG : and DOBSON, PHILADELPHIA : LONDON: AND BY OTHER PRINCIPAL OPTICIANS, BOOKSELLERS AND NEWSMEN IN TOWN & COUNTRY. 1829. GILL'S TECHNOLOGICAL & MICROSCOPIC REPOSITORY. I.-On the Microscope. By the EDITOR. (Continued from vol. IV., page 334.) WITH FIGURES. Additional particulars, on a singular production formed upon the body of a dead larva of a gnat. Since our last Article on the Microscope, the Editor has had another opportunity afforded him, of witnessing the growth of this production upon the dead body of another of these larvæ, and which was attended with still more singular circumstances than in the former case. The same effects again took place, of the production of transparent tubes, filled at their ends with small spherical bodies; and which tubes burst open as the water gradually dried up, and these spherical bodies swam about in all directions in a lively manner, as before, and the ends of the tubes generally remained empty, and quite pellucid; orifices or openings at their ends, through which their spherical bodies had been protruded being also visible, and as shown in fig. 1, of plate I., at a, a, a; and their filled ends appearing as exhibited at b, b, b. However, on the Editor preventing the farther drying up of the water, by replenishing the cell continually with more water, in order to prolong the experiment, he was surprised at finding the growth of the tubes to continue, under his eyes as it were, during the whole of the day; and that the tubes became lessened in size, and grew longer; they passing out at the VOL. V. B apertures remaining in the empty ends, as shewn at c, in fig. 1, until the field of view became filled with them. Others of the tubes also ramified or divided themselves into branches, proceeding from the main stems, in the manner shown at d, in our figure. We shall content ourselves with recording these singular facts, and leave the reasoning upon them to those who are pleased with endeavouring to account for these astonishing productions. The rapid growth of the tubes is perhaps one of the most singular circumstances attending this experiment; and we may add, those tubes which had not discharged their contents, at the time when the water was drying up, still continued to retain them during the whole period of its continuance. On the exuviæ of the larva of the ephemeron. This beautiful insect has, since our last article, thrown off three more exuviæ, all of which we have secured between slips of glass, as beautiful and permanent microscopic objects. Fig. 2 is a front view of the teeth, jaws, &c. copied from one of these exuviæ. On the exuvia of the pupa of the ephemeron. Mr. A. Pritchard has lately shown the Editor one of two of these exuviæ, which had been left by an ephemeron which he bred to the perfect insect. This exuvia had two straight appendages at its tail, instead of the three beautiful feathered ones belonging to its larva state; and it remained standing upon its legs, in the manner in which the ephe→ méron had quitted it, through an opening in its back. Our readers will find some highly interesting details respecting the ephemeræ, in our esteemed friend, Mr. Thomas Carpenter's communication for the present month. On the change of a nais into the pupa of a gnat.-The nais is a beautiful jointed eel-like animalcula, with a head also like that of an eel; and having a number of hair-like bodies at its tail, which it can extend or contract at pleasure, like the ribs of an umbrella. One of these, in the possession of the Editor, was lately found by him at the bottom of the water in the glass vessel in which he kept it, with its exuvia partly separated; and indeed, it was its shining bright appearance, that first led him to remove and examine the insect. Upon placing it under a microscope, he found that the greater part of it had completed its change, into a well known pupa of agnat, with two forked appendages at its tail; but that three joints of the body of the nais, considerably enlarged indeed, and its eel-like head, still remained without having undergone the change into the pupa state; the greater part of the the exuvia of the nais still adhering to it, and which is delicately ribbed or furrowed longitudinally. This fact has now explained the appearance of similar pupe of gnats, with small horns upon their heads, in glasses of water in the Editor's possession; and which he could not account for, as they only contained the nais. On the larva of the hydrophilus, or great water-beetle.The Editor has three very minute larvæ of this insect in his possession, not near the size of those figured in the last number of Goring and Pritchard's work, "On Living Objects for the Microscope;" indeed not larger than one of the legs of it; but nevertheless, nature has armed them with the same destructive weapons, and they are equally expert in using them. One of them lately attacked another larva, with beautiful bands of purple all along its whole body, and quickly mastered it, and then commenced swallowing it, under the observation of the Editor, with the assistance of a single lens of half an inch focus; in this manner he continued his work for an hour, his body gradually becoming of a purple colour, in consequence of receiving that of the purple larva within it, the actions of devouring and swallowing it being distinctly visible; at length he had swallowed all but the hinder part, this he bit off and left behind; being possibly annoyed by the numerous sharp and hooked claws attached to each hinder leg of the purple larva, and which form beautiful microsco |