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than any reform in road-engineering practice. Fortunately the pneumatic tire can hold its own with the solid or cushioned tire as an economical proposition for the motor-vehicle owner. In addition, a sliding scale of taxation in favour of the pneumatic tire is being adopted in many places, so that the position from the point of view of tho highway engineer should improve very considerably. The solid tire is blamed as being a contributory factor in causing corrugation. The damage varies according to the amount of wear which the tiro has undergone. The rubber itself also may have ceased to be resilient. The elastic property of the rubber is very much diminished, when under pressure, so that where tho pressure is greatest the modulus of elasticity of the rubber is least. Tests were carried out by the Bureau of Public Roads to determine the values of the impact on a pavement produced by vehicles with (1) pneumatic tires, (2) cushion tires, (3) solid tires. As a typical example of the results it was found that a motor-truck at a speed of 17| miles per hour gave with pneumatic tires an impact value of only 1-75 times the rear-wheel pressure on the road-surface, with the cushion tiros over three times, and with the solid tires 4-3 to 5-1 times ; that is, the cushion tires gave an impact value of 63 per cent, of the solid-tire average and the pneumatic only 36 per cent. It was also observed that the impact value for the pneumatic tiro increased only very slightly with an increase in speed. It was concluded that solid rubber tires should have a high rate of tire-deflection to produce the lowest impact, and worn tires should not be tolerated. In 1922 Messrs. Michelin, in France, also carried out tests to enable a comparison to be made of the effect of pneumatic and solid tires on road-surfaces. In tho case of tho solid tire the unit pressure on the area of contact varies from a maximum at the centre of the area to nil at the edges of the area. In the case of the pneumatic tire the intensity over the area of contact is practically uniform, since it is transmitted and distributed, by the air-pressure itself. It was deduced that the maximum intensity of pressure in the case of the solid tire exceeded tho maximum intensity of pressure in tho case of the pneumatic tire in the ratio of, roughly, 4£ to 1, The Michelin tests did not take into consideration at all tho question of impact. Labour Comparisons. In view of the extremely low costs that are sometimes reported from America, I took particular notice of the labour on construction jobs. My impression is that there is plenty of work done which ■~iust show very excessive labour costs. Great outputs are obtained from machinery, but I often noted that to enable the machinery to give the performance the jobs were simply flooded with men. This statement applies more particularly to concrete-work. Such skilled men as steam-shovel drivers, however, show a groat superiority over our New Zealand operators. In the shifting, rigging, and operating of such plant as pile-driving equipment, cranos, dredges, &c, the average American foreman is almost magical, and it is to such men that the credit of most of the speed records of tho United States in construction work is due. Propaganda and Education. In many spheres of modern civilized development the value of publicity and propaganda is more and more being recognized. In this respect there is no doubt that the United States loads the world. In attaining tho enormous road-building activity of the past few years the education of the people to the idea of good roads and. their value has been a most important factor. Every endeavour has been made to cultivate a sentiment. With the aid of the Press, the moving pictures, and many capable lecturers, the public at large has been forced to think " good roads." The Federal Bureau of Public Roads has taken a big part in assisting the movement. Not only at the commencement of a scheme, but also during the construction, the public interest is maintained by elaborate official statements as to the progress of the various works. In this way the public confidence is also gained. On many projects enormous signboards detail the outstanding features of the scheme, together with the names of the responsible persons. A public pride in the progress being made is fostered. Photographs. A very noticeable feature in. American engineering practice is the great extent to which photographs are used to illustrate reports, to support arguments, to assist in research, to record inspections, to advertise proposals, to give information to contractors, to estimate and record traffic congestion, and so on. As a typical example, the United States Federal Bureau of Public Roads, in making a study and criticism of 1,262 miles of the Californian highway system, took no less than 7,500 photographs, which were filed and. recorded. The pictures were taken at standard intervals of from one-tenth to five-tenths of a mile, and assisted greatly in arriving at a rational classification of the roads, besides forming an invaluable record for future reference. Supplementary close-up pictures of special features or defects were also taken. I think the camera to be more necessary to the highway engineer than the theodolite, and would urge its greater use in this country. Photography would be of tho greatest assistance in rationally and fairly administering the Highways Act. I would mention that the permanent staff engaged on the two vehicular tunnels being driven under the Hudson River in New York includes a particularly expert photographer, who is more or loss of a specialist in pictorially interpreting engineering features. The Southern Californian Edison Company at Big Creek, California, has set up in a suitable fixed position an automatic moving-picture camera which takes pictures at regular intervals throughout the day, so that a continuous record of the progress of the work is obtained. For the purpose of educating tho people up to realizing the full value of good roads the Bureau of Public Roads has a number of excellent films of road-construction, which aro shown on every fitting occasion, and loaned to public bodies desiring to foster a " good roads " sentiment.