verticals passing through the center of gravity of the voussoirs. Abstract of the operations to be performed. Determination by geometrical means of the pressure and resistance against slipping. 14. Co-efficient of stability of arches from the springing. Manner of finding the outline of an arch for a certain given co-efficient. Stability of a cylindrical arch on its piers. Thickness of the piers. Considerations relative to the value of the co-efficient of stability. Stability of an arch on the base of its foundations. Filling in and depth of the foundations of piers. Extension of the geometrical methods serving for the determinations of the pressures and thicknesses of piers in case of cross vaulting, arcades, and spherical vaulting. 15. Investigation by analysis of the pressures and resistances of an arch. 1st. Hypothesis of a plat-band; stability at the springing charge necessary on the coussinet; stability of the plat-band on its piers; thickness of the piers. Squaring of a tie-beam of iron which annihilates the pressure. 2d. Hypothesis of a semicircular vaulting with arched extrados. Pressures and resistances. In similar arches the pressure is proportional to the square of the radius. FOURTH PART.-HYDRAULIC CONSTRUCTION. 1st. Classification of ground on which it may be necessary to place a foundation. Soundings. Their object. Various kinds of sounding line. Dams in earth, and in wood and earth combined. Case of an unstable foundation. Construction on rock. Thickness of dams and of the clay work. General disposition of a dam. Bottom-springs. Means of choking or smothering them or of diverting them. Use of sunk dams. Service bridges. Their height and disposition. Railways in great constructions. Their disposition. 2d. Summary review of draining or pumping machines. Choice between the different methods of draining. Table of the useful effect of such machines. Pile driving. Pile driving machine with hand ropes. Preparation of the pile and operation of driving. Pile driving machine with catch. Choice between the two kinds of pile driving machines. Precautions to be taken in the driving of piles. Distribution of piles, the space to be left between them, and the squaring of them. Disposition and driving of planks. Method of drawing up piles and planking. Execution of a foundation on piles. Driving stakes out of water. Machine for squaring piles. 3d. Parafouilles. Their object and construction. Foundations in mortar under water. Preparation and immersion of the mortar. Examples. Thickness of sunk dams with the enceint in mortar. 4th. Foundation frames and platforms. Their object and their construction. Preparation of the foundation frames in masonry. Foundation by packing. Foundation by coffer-dams. Details of a coffer-dam. 5th. Foundations on solid gravel. Properties of gravel. Case where it is advantageous to make use of gravel. Examples. Foundations on sunk wooden piles, in gravel, and in gravel and mortar. Foundations on quicksand. Species of foundation to adopt according to the nature of the ground. 6th. Banks of reservoirs. Conditions which should be fulfilled in their establishment. Banks in earth; their profile; revetments to protect them; the wet slope; sort of remblai; precautions which exact a large remblai. Banks in remblai and sustaining walls combined. Banks entirely in masonry; movements observed in walls; most suitable profile. Comparison between banks in earth and masonry. Works which are employed in connection with banks of reservoirs. Dikes of inundations. Their profile; defense of their slope against the action of water; their establishment and works in connection with them. 7th. Batardeaux in the ditches of strong places. Situation; profile; details of construction. Weirs. Their object; effect of a weir in a current. Advantages of the wedge or circular form. Height to give to a weir; and longitu dinal form of the swelling occasioned by a horizontal dam. Construction of weirs with vertical walls, with a long slope down the stream. Injuries to which weirs are liable. Profile to adopt according to the nature of the ground. 8th. Sluice-dams, their object; form of the piles; distance apart, and dimensions. Details of construction. Various kinds of apparatus for opening and shutting sluice-dams. Play of a revolving gate. Calculation of the dimensions of the two half sluice gates and of the wicket. Carpentry of a revolving gate. Movable dams with iron wickets. Modifications to render them applicable to the retention of water at a greater height than 2.80 meters. 9th. Navigable locks. Canal lock; its management; form of the chamber; profile of the cheeks. Trace of the pier on which the gates work. Means of filling and emptying the chambers. Means of raising the paddle-valves. Wood-work of the gates sheathed in timber. Planes. Details of the pivots, collars and rollers. Arrangements for the management of the sheathed gates, 10th. Gates sheathed in wood; curves. Ties of cast-iron, and lining in wood or sheet-iron. Cast-iron gates. River Navigation.-Advantages and disadvantages of water transit. Conditions of a navigable river. Works for the improvement of the navigation on a river. Artificial Navigation.-Classification of canals. Conditions which determine the best position for a summit level. Search after a minimum of elevation. Expenditure of water at the summit level. 11th. Principal processes employed to economise the water in passing through a lock. Profile of a navigable canal. Deep cuttings; their profile. Great landslips and means of remedying them. Tunnels; their profile. Piercing of a tunnel. 12th. Bridges in masonry. Position; breadth of the roadway; outlet to be left for the water; size and form of the arches; trace of the surbased arches on more than five centers. Expansion of the bridge-heads. Profile of the arch. Thickness of the piles and abutments. Apparatus for the arches and bridge-heads. Parts above the arches. Leveling with the banks. Fixed and movable centerings. Removal of the centerings of arches. 13th. Wooden Bridges composed of straight pieces. Arrangement of the stakes and starlings. Different construction of the openings according to their span. Arrangement of the platform. American Bridges.-Arrangement of the earliest form of bridge on Town's system. Height of the trusses constructed in the form of trellis-work. Modi fications introduced to increase the resistance of the bridge. Calculation of the resistance of the trusses. Arched frame-work of bridges. Composition of the arches. Junction of the straight beams with the arches. Cast-iron Bridges.-Different systems. General principles of their construction. Aqueducts in masonry; in cast-iron. 14th. Suspension Bridges.-Equation of the curve of the chains and construction of this curve. Tension supported by the suspension cables, their thickness. Influence of the length of the flèche upon the tension of the cables. Inconveniences resulting from a long flèche. Vibrations and means of diminishing them. Limits of length of the flèche. Length of the curve of suspension. Causes operating to vary this length; means of obviating the effects produced by them. Length of the suspension rods. Number of supports to be adopted. Thickness of the piles. Points at which the fixing cables are to be attached. Advantages and disadvantages of chains composed of bars and of cables of iron wire. Some details of construction. 15th. Drawbridges.-Conditions which they must satisfy. General principle of their balance. Drawbridges with Plyers.-Special theory of this bridge. Reduction of it to practice. Alteration of equilibrium and means of remedying it. Disadvantages of the drawbridge with plyers. 16th. Spiral drawbridge of Captain Berché. Trace of the spiral. Determination of the radius of the chain-roller, and of the greatest radius of the spiral. 17th. Drawbridges with variable counterbalances, invented by M. Poncelet. Construction of the chains of the counterbalance. Establishment of the leverage. Calculation of the counterbalances for the special case of the pulleys in front corresponding to the axis of the platform. Influence of the nature of the chains. Method of allowing for the weight of the small chains. Definitive construction of the chains of the counterbalance. Provision of loose cords. 18th. Succinct ideas upon the motion of the sea, and its action on the shore. Undulating movement. Height of the waves, and depth at which the agitation is perceptible. Effects of the waves on the coasts. Tides; spring-tides; neap-tides. Height of tides and hour of flood. General currents. Action of the sea on its shores. Protection of level and steep shores. 19th. Sea-ports. Requisites of a good port. Ports in the Mediterranean. Conditions of a good roadstead. Moles and breakwaters. Ocean ports, channel tide-dock, floating dock, and sluice of floating dock, laying-up dock, and sluice for the ditch of fortifications. General arrangement of a harbor. 20th. Construction of moles. Stones dropped for foundations. Profile of a loose heap. Volume of the materials which insure their stability. Settling of masonry resting on a heap. Instances of masonry constructed at sea. 1. Wall of Cherbourg. 2. Fort Boyard. Piers.-Direction, length, form of interval between, and profile of piers. Their construction. Passages reserved through piers. Project for an struction: Drawing,.. Memoir, 42 $} ° } 9 Representation of an existing Each day is equivalent to 44 building or a part of a building by hours' work. means of plans, sections, and ele- The sketches are executed to Study and preparation of a project of a building, in accordance with certain given data. sary. The drawing prepared from the sketches is made on the scale of 1-100th. This work, common to the students of the two arms, is an application of the first part of the The sketches, the result of the course. first study, are made in pencil; the The scale for the drawing is in drawing is the fair copy of the general 1-200th for the plans and sketch, modified as may be neces-elevations, and 1-100th for the sections. It is restricted by the The memoir contains an expla- condition that the whole of the nation of the rules and principles drawings should be given on a which must be observed in the single sheet of paper. construction of buildings, and the The details need only occupy grounds on which the dispositions half a sheet of paper, and its contained in the building have scales must depend on the size of been adopted. the objects to be represented. The abstraction of the measure- The project for a building is an ments and their reduction to the application of the two first parts proper elements, and the estimates, of the course, as well as of the are prepared in conformity to the 1st section of the 3d part. instructions laid down for the En gineer Service in towns: these Determination of the profile for The drawing is executed to the a revetment wall, according to scale of 1-100th. This work is an certain conditions. Verification application of the 2d section of of the stability of an arch, and the 3d part. calculation of the pier supporting this arch. In the memoir a short explanation is given of the theory relating to the strength of revetment walls and arches, as well as the results of the application of these principles to the particular case. Study and composition of a pro- The scale of the drawing is ject for a gront work of art on chosen in such a manner that the certain given data. project may be placed on a single 10 12 In the memoir an explanation sheet; generally it is 1-200th, or 1528 1834 is given of the principles and the smaller. results of the theories which are The project of a hydraulic conto be applied in making this pro- struction is an application of the ject The arrangements adopted 1st section of the 3d part as well in the project are discussed for the as of the 4th part of the course. foundation and all other parts of the construction. Total,.... 110 116 |