II. CALCULATING MACHINES. 7 



at the bottom of the central column to the second difference which is shown 

 on the left hand column. The effects capable of being produced by this 

 mechanism, when the gearing is altered, and the loose wheels belonging to it 

 are put into gear with certain figure wheels, is explained in Cabbage's Ninth 

 Bridgewater Treatise, together with the new views which it opened up to him 

 upon the subject of natural laws. 



The three upper wheels of the left hand column are separated from the rest 

 of the machine, and are employed in counting the natural numbers. In other 

 words, they register the number of calculations made by the machine, and give 

 the natural numbers corresponding with the respective terms of the table. 



Four half turns of the handle, two backwards and two forwards, are 

 required for each calculation, and the words " calculation complete " come 

 round upon a wheel at the top of the central column to show when this is 

 done. This wheel also shows, by the word "adjust," in what position of the 

 handle the figure wheels may be freely moved by hand, in order to introduce 

 different numbers or a different table. 



24b. Cabinet, containing tablets for making mathematical 

 calculations. Archceological Museum, Madrid. 



Rose wood cabinet, inlaid with ivory. In three divisions are thirty small 

 drawers, containing ivory plates with numbers and divisions for making mathe- 

 matical calculations. In the inside are the arms of the monastery of the 

 Escorial. Milanese work of the 16th century. 



25. Fanometer, or Calculating Machine. 



Edward Grohmann, Vienna. 



By this extremely simple apparatus, various arithmetical computations can 

 be performed with great readiness. 



25a. Calculating Machine for Multiplication. 



P. Nicholas Dadiane, St. Petersburg. 



26. Calculating Machine, for performing complex arith- 

 metical operations ; invented by M. Thomas of Colmar. 



Professor Henncssy, F.R.S. 



2 6 a. Calculating Machine for Adding, Subtracting, 

 Multiplying, and Dividing. 



Theodore Esersky, St. Petersburg. 



26b. Small Calculating Machine, encased in a pocket- 

 book. Theodore Esersky, St. Petersburg. 



26c. Ten Copies of Multiplication and Division Tables. 



Theodore Esersky, St. Petersburg. 



27. Wertheimber's Calculating Machine, applicable to 

 wheel work. Patent, No. 96161843. 



The Committee, Royal Museum^ Peel Park, Salford. 



28b. Original Calculating Machine, known as " Napier's 

 Bones." Lord Napier and Ettrick. 



One of the earliest attempts to construct a calculating machine, made by 

 John Napier, the inventor of logarithms. His method of calculating by rods 

 was published in a volume (which is exhibited with the machine) at Edin- 

 burgh in 1617. The apparatus was commonly known as " Napier's Bones." 



