ILLUSTRATIONS.

Fig. Page.

1. Early Type of Mechanical Cleaning Nozzle Using Compressed Air 6

2. Another Type of Compressed Air Cleaning Nozzle, Supplemented with Vacuum Pipe 8

3. Separators Used With Combined Compressed Air and Vacuum Machines 9

4. Piston Type of Vacuum Pump, Mounted Tandem With Air Compressor 9

5. Mr. Kenney’s First Renovators Vacuum Alone Being Used as Cleaning Agent 10

6. Air Compressors Arranged for Operation as Vacuum Pumps 11

7. Separators Installed by Mr. Kenney in Frick Building 12

8. Vacuum Renovator With Inrush Slot, Introduced by the Sanitary Devices Manufacturing Company 13

9. First Portable Vacuum Cleaner, Constructed by Dr. William Noe, of San Francisco, in 1905 16

10. Late Type of Spencer Vacuum Cleaning Machine, Operated by Multi-Stage Turbine Blowers 17

11. Type A, the Straight Vacuum Tool 26

12. Type B, with Wide Slot and Wide Bearing Surface 26

13. Type C, with Auxiliary Slot, Open to Atmosphere 28

14. Type D, with Two Cleaning Slots 28

15. Type E, with Inrush Slot on Each Side of Vacuum Slot 31

16. Type F, an Exaggerated Form of Type B 31

17. Tests of Three Renovators on Dirty Carpets 35

18. Cleaning Tests of Carpets Filled with Quicksand 39

19. Cleaning Tests Using 1 oz. of Sand Per Square Yard of Carpet 41

20. Three Series of Tests with Kenney Type A Renovators 45

21. Tests by Mr. Reeve, Using Type C Renovator 46

22. Tests by Mr. Reeve, Using Type D Renovator 47

23. Tests Showing Efficiency of Different Types of Renovators at Different Degrees of Vacuum 50

24. Early Type of Bare Floor Renovator 55

25. Later Type of Bare Floor Renovator 55

26. Another Type of Bare Floor Renovator 56

27. Bare Floor Renovator with Felt Cleaning Surface 57

28. Bare Floor Renovator with Unusual Form of Slot 58

29. Bare Floor Renovator with Hard Felt or Composition Rubber Strips 58

30. Bare Floor Renovator with Rounded Wearing Surface 59

30a. The Tuec School Tool 62

31. Round Bristle Brush for Carved or Other Relief Work 62

32. Rubber-Tipped Corner Cleaner for Use on Carved or Other Relief Work 62

33. Early Type of Upholstery Renovator 63

34. Upholstery Renovator with Narrow Slots to Prevent Damage to Furniture 64

35. Another Type of Upholstery Renovator with Short Slots 65

36. Hand Brush Type of Renovator 65

37. Form of Swivel Joint Connecting Stem to Renovator 72

38. Swivel Joint Arranged to Prevent Dust Lodging Between the Wearing Surfaces 73

39. Swivel Joint in Use 74

40. Another Use of Swivel Joint, Showing Possibilities of this Form 75

41. Operator Cleaning Trim of Door with Swivel Joint 76

42. Swivel Joint, with Screwed Union 76

43. Swivel Joint Having Ball Bearings 76

44. Action of Ball-Bearing Swivel Joint 77

45. Illustration of Defects of Plug Cocks 78

46. Bayonet Type of Hose Coupling, Introduced by the American Air Cleaning Company 82

47. All Rubber Hose Coupling Used by the Spencer Turbine Cleaner Company 83

48. Chart for Determining Hose Friction 86

49. Effect of Increase of Velocity on the Friction Loss 88

50. Another Test Showing Friction Loss Due to Velocity 89

51. Inlet Cock to Prevent Air Leakage when Not in Use 101

52. Type of Automatic Self-Closing Inlet Cock 102

53. “Smooth Bore” Pipe Coupling 103

54. Joint Made of Standard Pipe Flanges 104

55. Standard Durham Recessed Drainage Fittings Generally Used in Vacuum Cleaning Installations 105

56. Friction Loss in Pipe Lines 106

57-60. Diagrams Showing Operation of Brush and Carpet Renovators Under Different Conditions 110

61. Typical Floor Plan of Office Building Illustrating Number of Sweepers Required 114

62. Plan of Layout for Office Building Showing Best Location (at d) for Vacuum Producer 118

63. Vacuum Cleaning Layout for a Passenger Car Storage Yard 122

64. Arrangement of Piping Recommended as Best for Passenger Car Storage Yard 123

65. Good Location for Dust Separator Where Large Areas Are Served by One Cleaning System 125

66. Location of Separators at Centers of Groups of Risers for Large Systems 126

67. Early Type of Primary Separator, Used by Vacuum Cleaner Company 128

68. Primary Separator Used by the Sanitary Devices Manufacturing Company 128

69. Primary Separator Used by the General Compressed Air and Vacuum Cleaning Company 129

70. Primary Separator Made by the Blaisdell Engineering Co. 129

71. Secondary Separator Used by the Vacuum Cleaner Company 131

72. Secondary Separator Used by the General Compressed Air and Vacuum Cleaning Company 131

73. Secondary Separator Used by the Sanitary Devices Manufacturing Company 132

74. Type of Dry Separator Used as Secondary Separator 134

75. Form of Complete Separator Used by the Vacuum Cleaner Company 135

76. Complete Separator Brought Out by the Electric Renovator Manufacturing Company 136

77. Complete Separator Made by the American Radiator Company 137

77a. Interior Construction of Dunn Vacuum Cleaning Machine 140

78. Power Consumption and Efficiency of Air Compressor Used as a Vacuum Pump 143

79. Modification of Reciprocating Pump Made by the Sanitary Devices Manufacturing Company 144

80. Power Consumption and Efficiency of Modified Reciprocating Pump 145

81 and 82. Indicator Cards for Clayton and Modified Pumps 146

83. One of the Pumps Installed in Connection with the Vacuum Cleaning System in the New York Post Office, the Largest Reciprocating Pump Used for this Purpose up to the Present 148

84. Interior Arrangement of the Garden City Rotary Pump 149

85. Power Required to Operate Garden City Type of Rotary Pump 150

86. Arrangement of Double-Impeller Root Type Rotary Pump for Vacuum Cleaning Work 151

87. Rotary Pump Arranged with Double-Throw Switch for Reversing Pump 152

88. Power Consumption and Efficiency of Root Type of Pump 153

89. The Rotrex Vacuum Pump, Used by the Vacuum Engineering Company 153

90. Late Type of Centrifugal Exhauster Made by the Spencer Turbine Cleaner Company 154

91. Power and Efficiency Curves for the Spencer Machine 155

92. Interior Arrangement of Invincible Machine, Manufactured by the Electric Renovator Manufacturing Company 156

93. Power Consumption, Vacuum and Efficiency of First Types of Invincible Machine 157

94. Power Consumption, Vacuum and Efficiency of Invincible Machine After Valve Was Fitted to Discharge 158

95. Four-Sweeper Invincible Plant Installed in the United States Post Office at Los Angeles, Cal. 159

96. Centrifugal Pump with Single Impeller, Manufactured by The United Electric Company 161

96a. Test of Centrifugal Pump with Single Impeller 162

97. Steam Aspirator Used by the American Air Cleaning Company 163

98. Steam Consumption of Steam Aspirator 164

99. First Type of Controller Introduced by the Sanitary Devices Manufacturing Company, known as the “Unloading Valve” 167

100. Test of Controller Connected to Suction of 8-Sweeper Piston Pump 168

101. Type of Controller for Use on Pumps Without Valves 169

102. Regulator for Motor-Driven Vacuum Pump, Manufactured by the Cutler-Hammer Manufacturing Company 170

103. Inspirator Type Vacuum Contactor, Used to Control Pilot Motor of Cutler-Hammer Controller 171

104. Vacometer for Use in Testing Vacuum Cleaning Systems 190