348 NEGRETTI AND ZAMBEA, HOLBORN YIADUCT, E.G., 



s. d. 



1719 Stadiometer, as used in the Army - 300 



1720 Spherometer, to measure the diameter of bullets, &c., 



divided into O'OOl of an inch and millimetres . 5 10 



1721 Wire Gauge of German Silver, for measuring the 



diameter of Wires to '001 of an inch .... 1 15 



1722 Ditto ditto of larger size, to measure to -01 of a 



millimetre or '001 of an inch 1 15 



1723 Patent Wire Gauge (Milner's), to read outside and inside 



to '002 of an inch, circular form .... 2 10 



1724 Ditto ditto flat form 330 



1725 Off- set Rod, shod with Point, 10 -link .... 040 



1726 Ditto ditto 10-link to part in centre with Point 



and Hook 096 



1727 Ditto ditto 10 feet, jointed, to part in centre, 



ends plain ferrules 11 



1728 Pickets or Ranging Poles, painted three colours, with 



Iron Strap Shoes, 6 feet . . . per dozen 1 15 



1729 Ditto ditto 8 feet .... per dozen 220 



1730 Ditto ditto 10 feet 3 10 



1731 Flags, White and Red, fixed to Picket Poles or loose, 



per dozen 6s., 9s., 11s. 6d. and 16 6 



1732 Sounding Chain, Stout Iron, welded inch links with 



heavy lead (in Stout Case) 50 feet 7 7s., 100 feet . 11 



1733 Sounding Lines for Coast Survey, with weight, 50 feet, 110 



1734 Ditto ditto 100 feet 1 10 



1735 Negretti and Zambra's Improved Portable Helio- 



graphs, for Military Signalling, Surveying, &c. 



3 inch, per pair 10 10 8 inch, per pair 17 17 

 5 14 14 10 25 



1736 Lanterns on Stands for.Night Signalling, with key and 



shutter each 550 



1737 Heliostat Spencers, local, with one Mirror ... 990 



1738 Torpedo and G-un Directors as specially constructed by Negretti and Zambra 



for the Admiralty and her Majesty's Navy. Supplied to order. 



ARITHMOMETER OR CALCULATING MACHINE. Fig. 1738. 



In the present age, when so many calculations are required, it is a matter 

 of surprise that mechanical aids to abridge the mental labour involved are not 

 more used. The efforts made by inventors and manufacturers to perfect machines, 

 and the numbers that have been made, proves that many are alive to the facilities 

 they afford ; but it is undeniable that calculating machines, and foremost among 

 them the Arithmometer, are not so generally employed as their utility warrants. 

 When it is considered that by means of the Arithmometer long operations in the 

 fundamental Rules of Arithmetic can be performed with rapidity, unfailing accuracy, 

 and without appreciable mental effort, it should be in general use by Accountants, 

 Astronomers, Bankers, Electricians, Engineers, Surveyors, Merchants and others. 

 Members of the Actuarial profession early discovered the benefits to be derived 

 from the use of the Arithmometer, and they have constructed sets of Tables, and 

 made other calculations on it for some years past. 



As an instance of the rapidity with which results may be obtained, it may be 

 mentioned that, with the improvements lately introduced, eight figures can be 

 multiplied by eight figures in about fifteen seconds, and larger operations in 

 proportion. 



