246 KANSAS CITY REVIEW OF SCIENCE. 



5tood the test beyond the most sanguine expectations. Actual measurement 

 showed that the pavement had not moved one five-hundredth part of an inch 

 during two years, and it was never once repaired, while the asphalt on the 

 same street had never lasted more than two consecutive months without repairs. 

 The stone pavement which had preceded the asphalt was also in need of constant 

 mending. 



The repaving of a large portion of the superb drive-way in the Champs Ely- 

 sees was also done by this Wood Pavement Company, of London. These severe 

 tests demonstrated the perfection of the new system, and a French company was 

 formed which has latterly repaved the Grand Boulevards, the Avenue de I'Opera, 

 the Rue Royale, where night and day there is a stupendous traffic, the Rue de 

 Rivoli and many other of the principal streets and avenues — in all some 400,000 

 square meters, or about twenty miles of roadway. The system is now being 

 extended to the Boulevard Haussmann, and is to be carried out all through the 

 splendid new quarter on the left side^f-the River Seine. 



The only system now in use here may be briefly described as an artificial 

 stone pavement, perfectly rigid and smooth, covered with wood. In order to 

 pave the roadway it is first excavated to the depth of twelve inches. A founda- 

 tion of concrete six inches thick, composed of Portland cement, washed gravel 

 and clean sand, is then carefully laid, and made to conform exactly to the contour 

 intended to be given to the top surface of the roadway. Before this concrete is 

 set or dry, a layer of very fine mortar, also made of Portland cement and sand, 

 is spread over it in a semi-liquid state, which leaves a perfectly smooth surface. 

 When dry this artificial stone foundation is almost as hard as granite, and 

 forms an arch extending from curb to curb. All the weight of the traffic is 

 supported by this foundation ; the wooden blocks are used simply to protect it, 

 and at the same time to afford to the wheels a smooth, elastic and noiseless way. 

 The English and French engineers lay great stress on this point. On the con- 

 creted stone pavement or foundation, then, a wood covering, six inches deep, 

 is placed. The blocks, which are usually 6x9x3, are placed on end in direction 

 of the fibre, directly on the concrete foundation, in rows across the street, leaving 

 a space between each row of about three-eighths of an inch. Boiling asphalt is then 

 run into this space, and forms a species of shoe around each block, cementing 

 them all together and to the foundation. The remaining space between the 

 blocks, about five inches, is then filled with Portland cement grouting. The top 

 surface is covered with fine gravel, and the pavement is allowed to dry. 



The company guarantees to keep the pavement in perfect order for eighteen 

 years, the city paying them 5 francs 37 centimes per square meter per annum. 

 Of this the city retains i franc 95 centimes per square meter per annum as a 

 guarantee and sinking fund for repairs, etc. At fixed periods — every six years 

 — the pavement is inspected, and if it is found to be in good order, the sinking 

 fund is paid over to the company, and a new sinking fund formed. 



The greatest advantage obtained for the dwellers in this crowded capital by 

 the adoption of this pavement (Kerr's system) is the cessation of the crashing 



