TYPES OF ANCIENT AND MODERN MACHINES Page General knowledge lacking 5 Key-driven machine, first of the modern machines 6 Recording, the primary feature of adding machines that print 7 Validity and priority of invention 8 Description of Pascal’s invention 11 Constructional features of the Pascal machine 12 Increased capacity of modern calculator 13 Patent office a repository of ineffectual efforts 14 THE EARLY KEY-DRIVEN ART First attempt to use depressable keys for adding was made in America 17 Description of Parmelee machine 18 Foreign digit adders 18 Single-digit adders lack capacity 19 Some early U. S. patents on single-digit adding machines 20 Calculating machines in use abroad for centuries 21 First key-driven machines no improvement to the Art 21 Description of the Hill machine 22 Hill machine at National Museum 25 Inoperativeness of Hill machine 25 High speed of key drive 26 Camera slow compared with carry of the tens 26 Hill machine merely adding mechanism, incomplete as operative machine 29 Chapin and Stark patents 29 Description of Chapin machine 29 Inoperativeness of Chapin machine 30 Description of Stark machine 33 Inoperativeness of Stark machine 37 Nine keys common to a plurality of orders 37 Description of Robjohn machine 38 First control for a carried numeral wheel 41 Description of Bouchet machine 42 Bouchet machine marketed 43 Misuse of the term “Calculating Machine” 43 Description of Spalding machine 47 Prime actuation of a carried wheel impossible in the Spalding machine 49