trips have been made by the laboratory officers in the interests of the work, and certain control tests have been standardized and applied to construction work. While the volume of work during the past year has been comparatively small it has given opportunity for experience and standardization of methods which will be valuable in the event of the greater activity which the future may bring. Of the materials examined during the past year the larger number were tested for the Highway Department directly; a few for county and city officials. The following list will show the range and number of samples handled:

In addition to these tests made at the Corvallis laboratory, the following tests were made at a small control laboratory used in connection with a piece of bituminous pavement north of Independence:

A discussion of the testing of the various materials may be of interest. First it will be noted that the tests, from the nature of things, are of two classes-those which may be called preliminary tests, and those which may be called control tests. Those of the first class are made in connection with the preliminary survey for the proposed work to determine what materials in the locality will be suitable for use. The questions of transportation and most economical type of construction can then be considered in connection with the qual

ities of the different materials that are available, and the best solution worked out. The tests of the second class, or the control tests, are made while the work is in progress, and have for their object the maintenance of the proper quality and proportions of the materials as they go into the work. The nature of these tests depends upon the type of construction, the tests being made on samples taken by the inspectors on the actual work. The control tests, though usually of a simple character, are most apt to be neglected but are really of extreme importance because materials, and especially those from natural deposits, are likely to be quite variable in quality and grading. Consequently they require careful watching to maintain the proper standard of quality and proportions.

The tests that are applied to stone intended for highway construction have been standardized by the United States Office of Public Roads and Rural Engineering. They are such as will determine the following properties: Weight and porosity, resistance to wear, toughness, hardness, and cementing power. It is the possession of these properties in a requisite degree that determines the suitability of any given material for particular conditions.

In concrete, and especially in concrete for roads the sand or fine aggregate is a most important ingredient. It is safe to say that more concrete failures are due to poor sand than to poor cement, yet very often no thought is given to the quality of the sand. Sand for concrete should be clean, hard, and well graded, and the tests applied are to determine these points. Briquettes are made using three parts of the sand under consideration to one part of cement, tests being made after seven and twenty-eight days and the results compared with those obtained from similar briquettes made of the standard testing sand from Ottawa, Ill. There is difference of opinion as to what ratio of strength should be demanded, but few favor a ratio of less than eighty per cent in concrete for road work, and many authorities require as much as 100 per cent or over. To determine the grading or granulometric composition of the sand sieves of the various sizes are used. Specifications generally limit the proportion of fine particles to a low percentage, a coarse sand being best for concrete.

The testing of cement has been thoroughly standardized by the American Society for Testing Materials. The methods have just recently been revised, and on January 1, 1917, a new set of specifications went into effect. Under these specifications tests are made for fineness, time of setting, soundness, strength of standard testing sand mortar, and chemical composition. Definite limits have been set for all these properties, and it is possible to detect cement which is unsound or otherwise defective.

In the various types of bituminous road surfaces the cementitious agent or asphalt must meet certain requirements if the work is to be successful. The analysis includes tests for consistency, purity, overheating, volatile content, brittleness, ductility, and sometimes others. The finished pavement to be strong and durable must contain the proper percentage of asphaltic cement and a mineral aggregate carefully proportioned, the whole being combined' at a proper temperature and laid with a sufficient degree of compression by rolling. These points are checked by density measurements, extraction of the asphalt by centrifugal machine, sieve analyses, and void determinations. For purposes of record or illustration sections of pavement are sometimes cut by means of carborundum dust and water applied by an endless wire saw passing over sheaves. Such a section exhibits very clearly the size and grading of the aggregate and the density of the pavement, and when photographed provides an excellent addition to the analysis record.

Mentioning briefly brick, stone block, and wood block roadways, it will perhaps suffice to say that tests have been perfected to judge these materials too; however, at present these types have very minor application in Oregon roads and the laboratory is seldom called upon for work on any of them.

Passing on to bridge materials we have timber, concrete, and steel principally. Tests on timber are seldom made, it being considered that when the stringers and other members pass the grading rules which are used in their selection they will reach certain strengths. Examination of concrete aggregates and cement has already been touched upon; the prin

ciples are the same here except that the requirements for the stone or coarse aggregate need not be so stringent as for a concrete wearing surface, for instance, a softer stone is often quite as satisfactory. Steel for the various purposes is purchased under appropriate specifications covering chemical composition, tensile strength, ductility, and lack of brittleness as shown by cold bending.

In the limited time available it is not possible to do more than to give a very general outline of the tests that are regularly applied; however, enough has probably been included to indicate the range of work to be handled, and to show its value.

In closing, the writer wishes to express the hope that if the road work in Oregon is to be reorganized the new code will do away with some of the loose-jointedness of the present system. At least in connection with the more important roads we need a more central control, so that specifications and methods may be standardized, and greater unity of effort developed. It is difficult to see how there can be real economy. or how a consistent program can be carried through in any other way.

By Dr. L. I. Hewes, District Engineer United States Office Public Roads and Rural Engineering

It is of considerable assistance in our study of a problem to approach it from a new direction. In ordinary affairs the word "investment" is well understood, and is associated with a complementary term, "income." Your attention is invited at this point on the program to the meaning which must be given to the term investment as applied to public highway expenditures. It will then be necessary to consider the question of highway income, and we shall try and arrive at some agreement as to the relation of these two terms.

At first thought a wide difference appears between public expenditures for highways and the idea of investment. By an examination of the evolution of highway disbursements we are led to ask the questions: What has been the evolution of highway expenditures? Are not modern highways performing larger services than formerly? Are they not positive instruments of commercial and social development? Do they not require financing of a more intelligent and able type than ever before?

Early in our history highways were crude. They served as stage routes, incomplete and abhorrent. When the railroad came it was a relief to abandon them to local service. For half a century the financing of highway construction and intermittent repair was a matter of local taxation, and irksome, as the device of statute labor indicates. The stage of disintegration of the highways was the principal stimulus for action. There was almost no attempt to fix a highway standard and then to create a public fund for keeping to that standard.

This method of hand-to-mouth financing had by 1891 begun to reach the limit of public endurance. Possibly to the League of American Wheelmen belongs the credit of first rousing the State of New Jersey to improve road conditions. There were no first-class roads in this country at that time. County officials were conscious of the inadequacy of the finances, but less willing to admit defects in the organization.