18
INDEX.
[Class X.
Bueitiiaupt. Theodolite; mode of graduating; pro-tection of the vernier circle by glass; level ;peculiar construction ; mining theodolite ; descrip-tion, 254.
Luttig. Levelling protractor, 255.
Kinzelhach. Surveying cross; description; diasti-rnetcr; "Wollaston's goniometer, 255.
Imperial Polytechnic Institute of Vienna. Level;construction ; improvements ; adaptation; smalllevels ; pocket levels; rulers for plane table survey-ing, 255.
Imperial Ijorsk Works. Levelling instruments andstand; workmanship, 255.
Burt. Astronomical compass; construction ; adaptation;
STANDARD MEASURES OF LENGTH, 255.
Whitworth and Co. Standard bar measure ; construc-tion; powers; how applied; description of tests;suggestions for improvement, 255.
Baumann. Bessel's standard measure ; construction ;mode of making comparisons ; delicacy ; eliminationof error, 256.
Simms. Standard yards; methods of support by Pro-fessor Miller and Rev. R. Sheepshanks; comparisonof relative merits ; standard scales, 256.
DIVIDING MACHINES, 257.
Ackland. Dividing machine ; usual method of gra-duation ; Mr. Ackland’s method divided into threeprocesses; description; example, 257.
Perreaux. Line divider; principle and construction,257.
Froment. Divided metre ; Froment’s screw ; applica-tion of electricity, 257.
Conservatoires des Arts et Metiers. Gambey’sbrass metre ; platina metre; description ; standardkilogramme ; French coins of legal currency ; mea-suring rods and chains; measures of capacity, 257.
BALANCES, 257.
Introduction; varied nature of collection; beauty of work-manship ; Foods balance; enumeration of the variousmonies of construction not adopted; Wollaston's methodof checking oscillation the most simple and efficient;division of the scale , 257.
Ludwig Oeutling. Balance; beam coated with pal-ladium ; balance to carry one kilogramme in eachpan; description, 258.
Dover. Balance; workmanship equal and similar tothat of Robinson; mode of adjustment; substitutionof links for silk threads, 258.
Fox. Balance for small weights; adjustment of thebeams by magnetism; method of overcoming fric-tion, 258.
Marriott. Chemical balance; construction of thebeam ; peculiarities, 258.
De Grave, Short, and Fanner. Assay balances ; com-mercial balances; weights; measures of capacitv,&c., 258.
Baciie. Large balance; construction and adjustment;small balance, 258.
Delf.itl. Balance; avoidance of screw adjustments;adapted for weighing gases; chemical balance; re-marks u]K>n construction ; assay balance, 259.
Collot. Balance ; assay balance, 259.
BEranger. Balances for the counter; steelyard; doublesteelyard; model of a machine for determiningpressure; Peso compteur , or weighing-machine;reason for not awarding a Medal to M. Beranger,259.
Sacre. Balance ; construction ; its peculiarities ; sus-pension of the pans ; beauty of workmanship; assaybalances, 259.
Oertling. Balance; construction and mode of adjust-ment ; attachment of two thermometers ; their posi-tion objectionable ; two small balances, 259.
Reimann. Balance; mode of effecting the adjustmentof the knife edges; adoption of the circular level,259.
Hoffmann and Eberiiardt. Balances for apothecaries,259.
Luiime. Chemical balances : their capabilities, 259.
Batka. Kusche’s small balance, 259.
Dolberg. Balance; mode of checking oscillation ob-jectionable, 260.
Becker. Balance; construction, 260.
Nissen. Large balance; form of scale-pans objection-able; small balance ; assay balance, 260.
Littman. Balance; substitution of an additional index,for a graduated scale considered objectionable, 260.
Viberg. Chemist’s balance, 260.
COIN-WEIGHING MACHINES, 2G0.
Difficulties attendant upon the old method of weighing thegold coin; dissatisfaction of the public ; difficulty of weigh-ing with sufficient accuracy; causes as discovered by Mr.Cotton enumerated ; orercome by Mr. Cottons coin-weighingmachine ; success attendant uijon its use , 260.
Description of Mr. Cotton machine; construction ;mode of acting detailed ; saving of revenue effectedsince its use was established in 1S44, 200.
Smith. Coin-weighing machine; its principle and con-struction, 261.
Deleuil. Coin-weighing machine, designed by BaronSeguier; conjectural description of the construction ;the machine not being patented, the internal me-chanism was not examined, 261.
Suggestions by Sir John Ilerschel for the construction ofa coin-weighing machine, 262.
Collection of balances in the Exhibition satisfactory ; remarksupon the omission of self-iceighing machines for smallweights, 262.
Imjx)rtunce of the air-pump ; remarks upon construction ;observations in favour of those exhibited ; Eewman, exhi-bitor of the best air-pump , 262.
Watkins. Double-barrelled air-pump; Grove's prin-ciple, 262.
Knight and Sons. Air-pump on Siemen’s patent, 262.
Varley and Son. Air-pump ; new construction ; smalldouble-barrel air-pump, 262.
IIeywood. Rotary table air-pump, 262.
Gocerty. Air-pump. 262.
Ladd. Single-barrelled air-pump, 262.
Yeates. Double-acting air-pumps, 262.
Bryan. Double-action air-pump, 2G2.
Breton. Double-barrelled air-pump; form of construc-tion objectionable, 263.
Deleujl. Double glass-barrelled air-pump, 263.
Nissen. Double-acting single-barrelled air-pump, 2G3.
OPTICAL INSTRUMENTS, 263.
Importance of the telescope ; a solid substance substituted byWray jor fiint glass ; optical glass in the Exhibition ;Simms’ object glasses ; Chance's disc of glass ; Dayuct;Bayerle ; Bertaud; Duboscq-Soldl , exhibitor of physicaloptics ; microscopes ; lighthouses , £‘c., 263.
TELESCOPES, 263.
Vaiilf.y and Son. Apparatus for Gregorian telescopes ;details of its construction ; remarks upon the advan-tages of the Gregorian form of telescope; portableGregorian telescope ; construction. 263.
Ross. Telescope; object-glass of English flint glass;tests to which it was subjected, 264.
Callaghan. Telescopes for dcer-stalking, 264.
Salmon. Telescopes for ship's use, 264.
Richardson. Reflecting telescope, 264.
Boyle. Reflecting telescope, 264.
Wray. Refracting telescope; a solid substance substi-tuted for flint glass; results of the test to which itwas subjected, 264.
Watkins and IIii.l. Telescope, 264.
Marratt. Achromatic telescope, 264.
Harris and Son. Double-image telescope, 264.
Buron. Telescope; the object-glass of rock crystal;particulars necessary to attend to in working rockcrystal; Huygens ’ formula ; telescope supportedupon M. C’auchois’ stand; telescopes with terrestrialand celestial eye-pieces. M. Biot, 264.
Lebrun. Achromatic telescope ; introduction of a flintlens between the crown lens and joint focus; suc-cessful result of test, 264.
Kinzelbacii. Dialytic telescope, 264.
Buscii. Achromatic and other telescopes, 265.
Introductory remarks upon the large collection exhibited:importance of the microscope; application to geology;