A

Abutments, Well System of, 129.

Air, Compressed

Effect on Men, 81-83.

Cooling, 78, 79, 81.

Noxious, in Cylinder Sinking, 49.

Penetrating Pressure on some Substances, 74, 75.

Quantity required, 73, 75, 76, 78.

Temperature, Precautions, 80, 81.

Air-Compressors, Arrangement and Character, 77-79, 81.

Hydraulic, 79.

Old, 78.

Number of, 77.

Air Escape, Effect of, 74.

Air-Lift, Excavating Apparatus, 116.

Air-Lock, Arrangement and Purpose, 83-87.

Doors, Interlocking, etc., 84-86.

Floor, 77, 84.

Height, 84.

Light, 83.

Lighting, 81.

Position of, 86, 87.

Removal of Excavation in, 86.

Roof, 77.

Signalling Apparatus, 81, 85, 86.

Size of, 84, 85.

Temperature, 80-81.

Air-Pipes, 84.

Air-Pressure

Advisable, 73-76.

Declining, Effects of, 76.

Formula, 75.

when Injurious to Men, 80, 81.

when Springs Encountered, 76.

Working-hours in, 80.

Air-Pumps, Working Continuously, 73.

Air-Supply

Constant Discharge, 74.

Purifying it, Necessity of, 74, 81.

Air-Tightness of a Cylinder, 73.

Air-Waste in Sinking Cylinders, 73, 74.

Areas of Cylinder, Table of, 18, 19.

Artificial Islands, Pitching Wells upon, 124.

B

Bag and Spoon Dredger, when Useful, 101, 104.

Base of Cylinder Piers, Load on, 24-31.

"Blows" of Soil during Sinking, 46-48, 54, 71, 101.

Bracing Cylinder-Piers, 3, 4.

Brickwork, Penetrating Air-Pressure, 75.

Bruce and Batho's Excavators, 106.

Special Features, 101, 106.

Bucket-Dredgers

Construction, 100.

Defects, 96, 97, 99, 101.

Discharge, 100.

Form, 100.

v. Grab-Dredgers, 99.

Hoisting Apparatus, 102.

Improvements in, 101, 106, 110.

when Ineffectual, 94, 97, 106, 108, 109.

v. Jumpers, 96.

Lifting Power required, 98.

Shape of, causes Success or Failure, 99-101.

Size of, 97, 98, 100.

Suitability of Earth for, 95, 96, 99, 101, 109, 116.

Working Capacity, 99, 101.

Bull's Dredger, 108, 110.

Bursting of an Air-Lock, 83.

C

Compressed-Air System of Sinking, 70-72.

Adoption, 94.

Advantages, 72.

Dangerousness, 73.

Depth of Economic Adoption, 71-73.

Disadvantages, 72.

and Dredging, 94, 95.

Effects of, 70, 71, 81, 83.

Limiting Depth, 73.

Old and New, 70.

Precautions, 81.

Requirements, 70, 71.

Signalling Apparatus, 81.

Waste of Air in, 73.

Compressors, Air

Arrangement and Character, 77-79.

Number, 77.

Cooling Compressed Air, 78, 79, 81.

Cutting-Edge, Excavating around and under, 96, 97, 102, 104, 106.

Cutting-Ring, 5, 6.

Cylinder-Piers

Advantageous Application, 1, 2, 4.

Area required for Excavating, 63, 64, 97, 98.

Compressed-Air, Method of Sinking, 70-72.

Cost of Different Methods of Sinking, 71.

and Cribwork, to Resist Ice-Floes, 2.

Diameter required, 10-17.

Distance between, 5, 44, 45.

Forces Governing Stability, 23, 24.

Increased Stability, 4, 5.

Large v. Small, 5, 8,9.

Limiting Height, 13, 14.

Load on Base, 24-33.

and Opening-Bridges, 4.

Position, 5, 8.

Shortening Spans, 5.

Sinking, 40-50.

Surface Friction, 33-39.

Unsuitableness, 3.

Water-tightness, 67.

Weights, Diagrams and Formulae, 11, 12.

Table of Areas, etc.

v. Wells, 1, 2.

D

Design of Bridge-Pier, Determining, 1, 2, 24, 25.

Diack's Excavator, 108.

Diameter required, Cylinder Bridge Pier, 60-62.

Dimensions of Rings, 6, 7.

Discharging Material through Air-Lock, 85, 86.

Distance between Cylinder-Piers, 5.

Divers Helmet,

Muddy Water, 82.

Precautions, 82.

Rough Weather, 82.

Signalling, 81.

Dock Walls, Well System of, 116, 126, 129.

Doors, Interlocking Air-Lock, 85, 86.

Dredging Apparatus for Cylinders and Wells (see also Excavating Apparatus)

Advantages, 91.

Bag and Spoon, Useful Application, 101, 104.

Bucket, when Ineffectual, 94-97, 106, 108-110.

v. Compressed-Air System, 94, 95, 110.

Construction, 100, 101.

Defects, 96-98.

Design and Purpose, 90-93, 95.

Disadvantages, 91, 92.

Expulsion System, 117.

Grab-Dredgers, 99.

Hoisting and Discharging Apparatus, 102, 103.

Improvements in, 100, 101, 106, 110.

Jumper and Bucket System combined, 93-95, 99, 105, 109.

Lifting Power required, 98.

Shape of, causes Success or Failure, 99-101.

Single v. Double Chain, 110.

Size of, 97-100.

Suitable Earth for, 95, 96, 99, 101, 109, 110.

Water-jet, 116-118.

Working Capacity, 99, 101.

E

Excavating, Working Area for, 63, 64.

by Compressed Air, 116.

Effective Action, 116.

Expulsion System, 117.

Water-pressure System, 117, 118.

when Ineffectual, 117.

Excavating Apparatus for Cylinders and Wells (see also Dredging Apparatus)

Adoption, 94, 95, 110.

Advantages, 91, 92.

Defects, 91, 92, 96, 97.

Design and Purpose, 90-93, 95.

Hoisting and Discharging Apparatus, 102, 103.

Improvements in, 101, 102-106, 110.

Jumper and Bag Dredgers, 108-109.

and Bucket System combined, 93-95, 99, 105, 109.

Lifting Power required, 98.

Screw for Loosening Soil, 107.

Shape of, causes Failure or Success, 99-101.

Size of, 97-100.

Suitability of Earth for, 95, 99, 101.

Various, Notes on, 103-111.

Working Capacity, 101.

Excavation, Discharging Pipe through Air-Lock, 85, 86.

Method of, in Cylinder, 87.

Removal of, in Air-Lock, 86.

Excavator-Pumps, 111, 112.

Explosives for Removal of Obstructions, 55.

F

Floor of Air-Lock, Pressure on, 77.

Flotation Power of Cylinder, 19-23.

Form of Cylinder Rings, 5, 8, 9.

Foul Air in Cylinders, 49.

Fouracre's Dredger and Spider Clay Cutter, 106.

Frictional Resistance, Earth on Cylinders, 33-39.

G

Gatwell's Excavator, Special Features, 105, 106.

Grab-Dredgers

v. Bucket-Dredgers, 99, 100.

Construction, 100, 109.

Object, 99, 109.

Gradual Pressure Room in Air-locks, 83.

H

Hearting

Contraction, etc., 67.

Depositing in Compressed Air, 67.

under Hydrostatic Pressure, 67.

Deposition, 66, 69.

Grout, for filling Cavities round the Cutting Edge, 66.

Purpose of, and Material for, 65, 66.

Surface of Base before Deposition, 66, 111.

Watertight, Importance of, 67, 68.

Height, Limiting, of Cylinder Pier, 13, 14.

Hoe-Scoop, or Indian Jham, Usefulness of, 101.

Hoisting and Discharging Apparatus for Dredging Machinery, 102-103.

Hydraulic Method of Removing Obstructions, 56.

I

Inclined Cylinder

A Cause of, 57.

"Righting,", 56, 57.

Iron, Cast, Penetrating Air Pressure, 74.

Iron Cylinders, Advantages of, 1, 2.

v. Well System, 1, 2.

Iron Rings

Dimensions of, 3, 4.

Object of, 3.

Islands, Artificial, for Pitching Wells upon, 124.

Ive's Excavator, 107.

J

Jham, Indian, or Hoe-Scoop, Usefulness, 104.

Joints, Cylinder Rings, 6, 7.

Jumper

Chiselled Rail, 105.

Rail, 108.

K

Kentledge

Calculation, 60-65.

Cast, 58.

Large and Small Cylinders, 59, 60.

Methods and Precautions, 58, 59.

Permanent Hearting for, 59, 60.

Quantity required, 64, 65.

Resistance to be Overcome, 61, 62.

Thickness and Weight of Casing required, 62, 63.

Top, Inside, and Outside, 58, 59.

Unobstructed Area required in Cylinder, 63, 64.

Water-tank, 58, 59.

L

Large Cylinders v. Small, 5.

Leakage of Air in a Cylinder, 73, 74.

Leslie's, Sir Bradford, Rotary Plough and Boring head, 111-113.

Lifting Apparatus, Dredging Machinery, 102, 103.

Lighting

Air-Lock, 81.

Working Chamber, 88-90.

Limiting Depth, Compressed-Air System, 73.

Height of Cylinder, 13.

Load on the Base of a Cylinder Foundation, 24-28.

Safe, 26-31.

Table of Safe Loads, 31-33.

M

Machinery, Air-Compressing, 77.

Character and Arrangement, 78.

Making-up Ring, 7.

Milroy's Excavator, 107.

Molesworth's Dredger, 111.

Mooring Pontoons, 51, 52.

O

Obstructions in Sinking,

Advantage of Compressed-air System, 54.

"Blows" of Soil caused by, 101.

Explosives, Use of, Questionable, 55, 56.

Hydraulic Method of Removal, 56.

Methods of Removal, 53-57.

Removal of, 51, 95.

P

Pipes, Air, 84.

Pontoon System of Floating-out Cylinders, 51, 52.

Improvement in, 52.

Precautions necessary, 51-53.

Small Cylinders, 52.

Top and Bottom Guidance necessary, 51.

Portland-cement Concrete Cylinders, 3.

Position of Air-lock, 86, 87.

Cylinder Piers, 5.

Pressure, Normal, of Soil, 28.

Pumps for Sandy Water, 111, 112.

Purification of Compressed Air, 81.

Q

Quay Walls, Well System of, 116, 126, 129.

R

Rammer for Hard Soils, 104, 105.

Reducing Ring of Cylinder, 4.

"Righting"

an Inclined Cylinder, 56, 57.

an Inclined Well, 125, 128.

Rings of Cylinder

Contraction of, 67.

Cutting-Ring, 7.

Dimensions of, 6, 7.

Form of, 5.

Making-up Ring, 7.

Thickness of, 6.

Roof, Air-Lock, Pressure upon, 77.

S

Sand-Pumps

Arrangement and Use of, 111, 112, 114.

Combined with Cutters, 111, 112.

Ead's, 116.

Kennard's, 108.

Working, 111, 112.

Sandstone, Penetrating Air-Pressure, 75.

Shafts to Working Chamber, 85, 87, 88.

Signalling Apparatus

Air-lock, 85.

Compressed-Air System, 81.

Sinking Cylinders

"Blows" of Soil during, 46, 49.

Close together, 44.

Comparing Cost of, 40.

Compressed-Air Method, 70, 72.

Cost of Different Methods, 40, 71, 73.

Danger of Sudden Sinking, 44.

Earthbound, 48, 49.

General Notes, 40.

Loose Soils, 48, 49.

Methods of, 40-42.

Noxious Gases Encountered in, 49.

Obstructions in, 53.

Outside Subsidence caused by, 46, 48.

Pontoon, System of Floating-out, 51, 52.

Precautions in, 45, 46.

Staging, 50, 51, 102.

Suddenly to be Avoided, 71.

Vertical Sinking Important, 43, 44.

Water-levels, Inside and Outside, 47, 48.

Sinking Wells by Compressed Air, 126.

Discontinuing, When Incomplete, 126.

General Notes, 124-128.

Rate of Sinking, 127.

"Righting" Them, 125, 128.

Small v. Large Cylinders, 5, 8, 9, 44.

Spider Clay Cutter and Dredger, Fouracre's, 106.

Stability of Cylinder-Bridge Piers, Forces Governing, 23, 24.

Staging, 9, 50, 51, 97.

in Exceptional Circumstances, 50, 51.

Fixed, when Impracticable, 50.

Use of, 50.

Stoney's Helical Excavator, 111.

Strong's Excavator, where Useful, 105.

Subsidence of Ground during Sinking Cylinders, 46.

Supply Shafts, 87, 88.

Surface Areas of Cylinders, Table of, 19-22.

Surface Friction, on a Cylinder Pier, 33-39.

Depth, Influence, 37, 38.

Reliable, 38.

Dry and Wet Surface, 37.

Large v. Small Cylinders, 38.

Table of Values, 39.

T

Telescopic Dredger, Furness and Slater's, 111.

Temperature of Air, Precautions, 80, 81.

Thickness of Rings, 5, 6.

Timber, Penetrating Air-Pressure, 74.

Top Ring of Cylinder, 7.

W

Water-jet Excavators, 112-118.

Water-sealing a Cylinder, 68, 69.

Thickness required, 69.

Weight of Cylinder Piers

Diagram and Formula, 10-12.

Tables of, 17-23.

Well System

Abutments, 129.

Advantageous Application, 1, 4, 118.

Conditions when it may Fail, 1, 118.

Curbs, 122.

Heavy v. Light, 122.

Material for, 122, 123.

Securing Steining to, 122.

Excavation, Internal, 127.

Form of Wells, 119, 122.

Grooving and Interlocking Wells, Objections to, 122.

Hearting, 128.

Height of Rings, 125.

Large v. Small Wells, 118, 119.

Methods of Sinking, 121, 125.

Modern Practice, 118.

Quays and Dock Walls, 116, 126, 129.

Sinking Wells, 124.

Close together, 119, 128.

Steining, 120-122.

Strains on Wells, 119.

Tie Bolts, 121, 122.

Wood, Penetrating Air-Pressure, 74.

Working Chamber

Arrangement and Construction, 87.

Height and Size, 87.

Lighting, 88-90.

Purpose of, 87.

Supply Shafts to, 87, 88.

Temperature, 80, 81.

Water Ingression, 88.

Working-hours under Air-Pressure, 80.