EXHIBITION, BRITISH INDUSTRIAL. 



427 



of ancient MS., and one of a page of Domesday 

 Book. The photograph, by a simple and cheap 

 process, is transferred to a zinc plate, whence 

 any number of copies can be taken off by the 

 ordinary plate printing process. 



F. Joubert exhibited a series of very beauti- 

 ful pictures burnt in on glass, a marvellous 

 adaptation of the photographic art in an abso- 

 lutely new direction. By a pure photographic 

 process he produces on the glass, in ceramic 

 colors, a picture, which, by exposure to heat 

 in the furnace becomes burnt in like any other 

 picture on glass or china. By a careful and 

 artistic manipulation he has been able to pro- 

 duce effects in several colors. The process has 

 been perfected, and a cheap and artistic orna- 

 mentation of our windows is brought within 

 the means of the many. 



CLOCKS AND WATCHES. The great dial 

 around the stained glass window at the eastern 

 end of the nave, measuring nearly 40 feet in 

 diameter, was the first lion of this class. It 

 was worked by a clock made by Dent. 



Another gigantic work, termed par excel- 

 lence "The Great Exhibition Clock," was 

 placed in the central tower of the south side of 

 the exhibition building. The maker is M. Ben- 

 son, of Ludgate hill. Its special peculiarity is 

 a new double lever remontoire, the application 

 of which diminishes the friction or retarding 

 force, and allows of great motive power, even 

 to the extent of 20 tons, being used without 

 disturbing the time-keeping qualities. In all 

 cases where the works of a clock are at a great 

 distance from the dial, as in this case, the outer 

 dial being 300 feet from the works, a great mo- 

 tive power is requisite. 



The great watch and clock makers of Clerk- 

 enwell exhibited in full strength. After Clerk- 

 enwell, but at some distance, came the watches 

 of Coventry ; and last of all, the prettiest and 

 cheapest, but much inferior, watches of Swit- 

 zerland. In this class all the great watch and 

 clock manufacturers of England showed their 

 masterpieces of workmanship. There were 

 reversible chronometers, steam clocks, marine 

 chronometers, astronomical clocks, geographi- 

 cal clocks, silent clocks, skeleton clocks, Lilipu- 

 tian alarm clocks, electro-magnetic clocks, key- 

 less watches, electric clocks, mercurial time- 

 pieces, clocks showing mean time and longitude 

 at important places, and galvano-magnetic 

 clocks ; and gold and silver watches of every 

 description. 



ELECTRIC TELEGRAPHS AND ELECTRICAL AP- 

 PARATUS. It has been aptly observed that the 

 practical influence of electrical inventions met 

 the visitor at the very threshold of the Exhibi- 

 tion Building, where the " Magnetic Tell-Tale" 

 of Prof. "Wheatstone was attached to some of 

 the turnstiles, and this, in a measure, controlled 

 the financial department. This instrument was 

 worked without battery power of any kind. 

 The electricity was generated by a peculiarly 

 constructed magnetic machine, so connected 

 with the axis of the turnstile as to discharge a 



current of its force at each revolution of the 

 stile. Thus, each visitor, on passing through 

 it, unconsciously and telegraphically announced 

 his or her arrival to the financial officers in 

 whose rooms were fixed the instruments for 

 receiving and recording the liberated current, 

 which latter was conducted thither by a line of 

 copper wire laid along the building between 

 those instruments and the turnstiles, and metal- 

 lically connected to each. The registers thus 

 obtained formed a complete check upon the 

 money taken at the doors. 



The great improvements and numerous in- 

 ventions in electric telegraphy during the past 

 ten years were strikingly shown by the various 

 new instruments exhibited by the Universal 

 Private Telegraph, the British and Irish, the 

 Submarine, and other telegraphic companies. 

 Prof. Wheatstone's ingenious and beautiful Do- 

 mestic telegraphs were shown in working order, 

 and many inventions and contrivances to utilize 

 this valuable discovery. Mr. Tyer exhibited his 

 patent Train Telegraph. The apparatus for 

 the use of the signalmen comprise a telegraph- 

 ic needle for each line of rails in each direc- 

 tion, and a bell and gong, having different 

 sounds, the one for the up and the other for 

 the down line of rails in each direction. The 

 bell or gong is used to draw attention to the 

 approach or passage of a train, and by the 

 number of beats employed, to describe the 

 train : while the needles are used solely to 

 denote either t; line blocked," or " line clear ;" 

 and no signalman can alter his own instrument, 

 it being the duty of each signalman to work the 

 needles of the signalmen on each side of him. 



The most interesting and advanced of these 

 instruments were those which worked more or 

 less automatically. The automatic system of 

 Mr. Allan consists of three machines; the 

 punching machine is the first of these, and by 

 this the ribbon paper to be passed through the 

 sending machine is perforated with holes, rep- 

 resenting dots and strokes of the Morse alpha- 

 bet, at those points only where the current is 

 required to mark on the unperforated ribbon 

 at the receiving station ; next is the sending 

 machine, into which the perforated paper is 

 introduced. This machine winds up its own 

 clockwork, whereby the paper is drawn for- 

 ward, and stops of its own accord when the 

 message is completed ; and lastly, the receiving 

 instrument at the distant station, which is also 

 so arranged as to start its own machinery on 

 receiving the electric impulse, and stop it when 

 the perforated paper at the other end has pass- 

 ed through the sending apparatus. 



The British and Irish Magnetic Telegraph 

 Company exhibited a system of controlling tur- 

 ret and other clocks, the clocks being control- 

 led only, and not moved either in whole or part, 

 by electricity. The three clocks shown were 

 in all respects, excepting the pendulum, of or- 

 dinary construction, and would go without the 

 electric current, keeping their own time. The 

 pendulum is a hollow electro-magnet, oscillat- 



