xxvi LIST OF ILLUSTRATIONS. 



PAGE 



35. Loading cars, Speed natural-cement quarry 219 



36. Crusher for raw rock at Speed's mill 220 



37. Sections of kilns used in natural-cement plants 226 



38. Elevation and section of Campbell kiln 227 



39. Plan and details of Campbell kiln 227 



40. Kilns of the Lawrence natural-cement plant 228 



41. Kilns and coal conveyor at the Speed plant 229 



42. Kilns and kiln housing, Speed plant 230 



43. Kilns and loading tracks, Fort Scott, Kansas 233 



44. Sections of cracker for natural-cement grinding 239 



45. Sturtevant rock-emery mill 240 



46. Sturtevant rock-emery millstone 240 



47. Section of Sturtevant mill 241 



48. Berthelet separator 244 



49. Installation of Berthelet separating system 245 



0. Effect of plaster on set of natural cement 265 



51. Effect of salt on compressive strength, natural cement 266 



52. " " " " tensile " " " 266 



53. " " " " " " " " 267 



54. Tensile strength of Louisville cement 268 



55. ' ' " " Lehigh natural cements 268 



56. " " " Cumberland natural cements 268 



57. " " " Akron and Cumberland natural cements 270 



58. ' ' " ' ' natural cements, Cairo Bridge tests 271 



59. " " " Rosendale cements. 272 



60. " " " natural cements, Saulte Ste. Marie 272 



61. Effect of sand on tensile strength, natural cements 273 



62. Tensile tests, Saulte Ste. Marie 274 



63. Map of the U. S., showing location of Portland-cement plants Opp. 294 



64. Percentage of total output from different raw materials 303 



65. Working a thick limestone bed 311 



66. Working heavy horizontal bed of limestone 315 



67. Tunnel in cement rock. . 330 



G8. Open cut in cement rock 331 



69. Pit in heavy shale bed 358 



70. Shale pit worked on two levels 358 



71. Stripping a flat, shallow bed 368 



72. View of typical limestone quarry 369 



73. Temporary tracks laid to face 369 



74. Cableway in cement-rock quarry 370 



75. " " " " " 371 



76. Shale pit worked in two levels 371 



77. Hoisting from quarry worked in levels 372 



78. Steam shovel in cement-rock quarry 372 



79. Steam shovel in limestone quarry 374 



80. Dredge at marl plant 376 



81. Harris system of marl-pumping 377 



82. Marl-drying plant, Hecla P. C. Co 401 



