PAGE
Frontispiece, “Stone Age Calculating”
One of the Pascal Machines 10
Photo of Blaise Pascal 11
Parmelee Patent Drawings 16
Hill Patent Drawings 23
Chapin Patent Drawings 28
From the Stark Patent Drawings 32
From the Robjohn Patent Drawings 36
From Drawings of Bouchet Patent 314,561 40
Drawings of Spalding Patent No. 293,809 46
“Macaroni Box” Model 53
Photo of Dorr E. Felt 55
The First “Comptometer” 57
From Drawings of Felt Patent No. 371,496 58
Bill for First Manufacturing Tools of the Comptometer 68
Early Comptometer 69
Letter from Geo. W. Martin 71
Testimonial 72
Testimonial 73
Letters from Elliott and Rosecrans 74
From Drawings of Barbour Patent No. 133,188 78
From Drawings of Baldwin Patent No. 159,244 83
Baldwin Machine 83
From Drawings of Pottin Patent No. 312,014 88
From Drawings of Burroughs Patent No. 388,118 94
Photo of Wm. S. Burroughs 95
Drawings of Ludlum Patent No. 384,373 104
From Drawings of Felt Patent No. 405,024 112
Testimonial 117
Felt Recording and Listing Machine 118
From Drawings of Felt Patent No. 465,255 121
Felt Tabulator 126
One of the Early “Comptographs” 130
Photo of Gottfried Wilhelm Leibnitz 132
Leibnitz Calculator 133
From Drawings of Burroughs’ Patents Nos. 504,963 and 505,078 136
Burroughs’ Recorder 137
From the February 1908 Issue of Office Appliances Magazine 142
The High-Speed Calculator 148
Two Pages from Wales Adding Machine Co. Booklet 165
Moon-Hopkins Billing and Bookkeeping Machine 176
Napier’s Bones 179
From Drawings of Barbour Patent No. 130,404 180
Photo of John Napier 181
From Drawings of Bollee Patent No. 556,720 186