III. MISCELLANEOUS. 13 



42. Fetroff's Arithmetical Apparatus. 



M. Petroff, Kalouga. 



43. Arithmometer, with measuring apparatus, and the full 

 size skeleton of the square metre and cubic metre, folding up by 

 means of a hinge. frere Memoire Piron. 



43a. Counting Machine. 



P. N. Dadiane, St. Petersburg. 



43b. Calculating Machine. 



P. N. Dadiane, St, Petersburg. 



45. Model of Gas Meter Counting Machine. 



Council of King's College, London. 



46. Cavendish's Original Counting Machine. 



Council of King's College, London. 



III. MISCELLANEOUS. 



48. Apparatus for the Statistical Treatment of large 

 numbers of Seeds, &c., to sort them rapidly into classes 

 differing by regular gradations of magnitude, with the view of 

 testing how far the relative numbers in the several classes accord 

 with the results of the Law of Error or Dispersion. 



Francis Gqlton, F.R.S. 



It consists of a square box, having parallel bars fixed across its top at 

 equal distances apart. An equal number of similarly arranged bars are con- 

 nected by means of rods running along 1 tbeir ends, like the bars of a gridiron, 

 thus forming a framework that is laid on the top of the box. Hence there 

 are two systems of parallel bars in the same plane, one of which is fixed and 

 the other movable. When the frame is pulled forwards as far as it can go, 

 each of its bars presses along its whole length against one of the fixed bars, 

 and when it is pushed gently back the framework bars separate simultaneously 

 and equally from the fixed bars, and any objects that may have been laid 

 between their edges, and are small enough, will drop through. The bars are 

 bevelled along their opposite faces, in order to receive these objects. The 

 framework is moved by a screw turned by a ratchet wheel, which is itself 

 moved by the to-and-fro action of a handle between stops, one of which is 

 adjustable at pleasure. Hence, every time the handle is worked, the space 

 between the bars is widened by a definite space, and all the seeds, &c., whose 

 diameter is greater than the original and less than the final space, will drop 

 through. A tray, divided into compartments, slides beneath the box ; it is 

 pushed forward through the space of one compartment before giving a fresh 

 movement to the handle, and thus the seeds become sorted into the different 

 compartments. (This instrument was used to illustrate a lecture before the 

 Royal Institution on Friday evening, February 27, 1874.) 



