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
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. IV.

LONDON:

PRINTED BY W. SPIERS,

399, OXFORD-STREET;

EDITED AT GILL'S PATENT AGENCY & COMMISSION OFFICE,
125, STRAND, NEAR TO SAVOY AND WELLINGTON STREETS;

PUBLISHED BY THOMAS HURST, EDWARD CHANCE, AND COMPANY,
65, ST. PAUL'S CHURCH-YARD;

AND SOLD BY THE FOLLOWING OPTICIANS, viz:-

CAREY, STRAND; BANCKS, STRAND; WATKINS and HILL, CHARING CROSS;
P. CARPENTER, REGENT STREET; WEST, FLEET STREET; BATE,
POULTRY; and JONES'S HOLBORN:

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: LONDON:
LIKEWISE BY TRUETTEL and WURTZ: PARIS and STRASBURG:

and DOBSON, PHILADELPHIA :

AND BY OTHER PRINCIPAL OPTICIANS, BOOKSELLERS AND NEWSMEN IN TOWN & COUNTRY.

1829.

1

BIBLIO

MOTHE

GILL'S

TECHNOLOGICAL REPOSITORY.

I.-On the Microscope. By the EDITOR.

WITH A PLATE.

(Continued from Vol. III., page 327.)

On the Wheel-Animalcula, in continuation.-Since the publication of our last number, we have been frequently, at times, engaged in following up our discovery of the eyes of this animalcula, as published in page 322, with a figure of the snout or tube containing the eyes; since then, we have discovered minute fibrillæ around the end of that tube, and whether its mouth may not also be there, we cannot be certain.

We now add in plate I. other figures, showing the eyes in various situations, in order to leave no doubt upon this interesting discovery. In fig. 1 they are shown as in our former figure, at the end of the snout; in fig. 2, as placed between the wheels; and in figs. 3 and 4, as thrown backwards. In several of these figures, another slender tube is also shown, posited at the back of the snout which contains the eyes, and which has frequently been represented in works treating upon this singular animalcula, such as Baker's, and others; and generally in the side views of it. In fig. 3 is also shown an oval body, which frequently changes its place in the body of the animalcula, and, no doubt, is one of its eggs, of which we have seen many affixed upon the leaves of the lemna, and other aquatic plants, as well also as upon the sides of the glass vessels in which we have kept these truly interesting microscopic objects; sometimes we have even seen the

VOL. IV.

B