and paid for, properly demonstrated by following it.

10. The failure of some corporations to appreciate that, because on one occasion the employment of a so-called expert proved unprofitable, such instances are in the minority.

II. The failure of society and the engineering profession to protect both society and the profession properly as yet against the "quack."

12. The failure of many competent experts to so express themselves in their advice and reports as to leave themselves free from grounds for such criticism as Mr. Goodell makes on this point.

I take it that your editorial and Mr. Goodell's letter were published with the idea of warning against and, so far as possible, of preventing such failures. I think they deserve emphasis; hence this letter. Baltimore, Md. W. W. CROSBY.

TH

HE question of the practicability of the use of American rock asphalt has become a more interesting one now that, owing to the war, shipments from the European sources of supply of the natural bituminous limestone must be curtailed or cut off. The use of the natural bituminous limestone of Seyssel and Mons (France), Val de Travers (Switzerland), Limmer and Vorvohle (Germany) and Ragusa (Sicily) has been more or less general in the United States since 1872. The area of streets covered, however, has not been very large, owing to the high cost of freighting the entire volume of the surface material for so many thousand miles, and it has been laid almost entirely at seaboard cities, such as New York, Brooklyn, Philadelphia, Boston, New Haven and New Orleans

That the natural material gives a more durable finished surface than the asphaltic cement sand or concrete mixtures has been conclusively proved by the extraordinary low cost of maintenance where any care has been exercised in watching and promptly repairing any defects, which have rarely, if ever, been caused by ordinary traffic. In this country we have two natural asphalt rock asphalts-the limestone and the sandstone. The former is found principally in Texas and Oklahoma and the latter in Kentucky, with a less compact and more oily product in California.

The principal supply of the Texas rock asphalt is from Cline, Uvalde County.

The use of this material for street surfacing was begun in San Antonio and other Texas cities during the first year of this century. While the results in general were satisfactory, it was found that there was a lack of ductility in the surface that occasionally caused cracks in places where traffic was light or expansion and contraction had been severe.

After scientific and careful research and experimental work, it was discovered that an improvement could be made in preparing the material for application to the streets, and the writer was last June summoned to Texas to report on the new method.

Investigation showed that an addition of a small percentage of maltha (asphalt oil) gave a ductility to the asphaltic cement which not only afforded an added resilience and ductility to the surface mixture, but allowed of a denser and more compact mixture which permitted a greater comparison than with any artificial mixture of asphaltic cement, sand and lime dust under steam roller pressure.

The new method of preparing the material for application to the street surface is a most decided improvement on the European method. In Europe no attempt has been made to improve on nature, and the only deviation from the direct application of the heated powdered asphalt rock has been the use of rock from different mines, such as Seyssel and Ragusa, Neuchâtel and Vorvohle, or other mine prod

ucts where one limestone is more or less impregnated with bitumen or the material more or less porous in the natural state. By this method a rich and lean impregnation when mixed together will give the necessary 7 per cent to 10 per cent of bitumen which is required. With the Texas preparation, a better bituminous mixture is obtained and a more regula: percentage of bitumen.

The advantages of the fluxed material over the natural material as laid in the beginning of the century in Texas cities is that a ductility is given to the present surface which was wanting in the old construction, owing to the asphaltine in the natural rock being harder. The bitumen

A BIT OF THE NATURAL ASPHALT

in its original formation had undoubtedly been subjected to greater heat and the lighter petroleum evaporated by nature; therefore the new idea of adding maltha (asphalt oil) to the natural asphalt in the limestone gives a natural asphaltic cement with more elasticity or ductility.

Under the new method some three hundred thousand yards have been or are being laid in Houston, Beaumont, San Antonio and other Texas cities. How great an influence in paving this improved method of waterproof surfacing of streets and roads will have on city authorities in other states is largely a question of cost of transportation.

For country roads the Uvalde natural

rock can be applied either hot or cold on a macadam road with a thickness less than that required for city streets. Highly satisfactory results are reported from city enginecrs of three-fourth-inch surface rolled

in by the penetration method, with a final coat one-half inch thick where Kentucky rock has been used. For such work the powdered asphalt limestone will be found more efficacious than the asphalt sandstone.

O

NE of the leading trust companies of this city making a specialty of certifying to the genuineness of municipal bonds sends out literature on the subject under the caption "Safety Is the First Requisite in the Issue of Municipal Bonds," and lays particular emphasis on the necessity for issuing securities for the payment of which taxpayers are responsible, under a plan of issue providing adequate protection to the issuing community, the dealer, the banker loaning on the bonds as collateral, and the investor, who, in this instance, is the "ultimate consumer." The cry of "safety first" is perhaps nowhere more justified than in this connection, since the ordinary loose way of issuing this class of securities lends itself to all sorts of abuses and may justly be termed an open invitation to crime, so easily may spurious paper be issued and the fraudulent act remain hidden for months. Often the municipality itself invites trouble by requiring in its published notices of sale that the blanks be furnished by the purchaser of the bonds. So easy a method of obtaining money is nct to be overlooked by the unscrupulous, and duplicate issues are the result. It is to be hoped that every crime of this sort is finally brought to light and the perpetrator punished, but in spite of the popular theory that the criminal eventually reveals himself, there remains an uneasy doubt as to whether he may not sometimes successfully cover up all evidence of his wrong-doing and out of the earnings of his illicit capital repay the "loans" obtained by means of the duplicated paper.

We have pointed out only one of many routes by which lax methods of issue invite abuses. The fact that such lax methods prevail hinders in no small degree the free exchange of municipal securities between

investors, and in other ways unfavorably affects the value of securities which should stand supreme at the very top of the market and pass unquestioned from one investor to another.

It seems strange that the officials of any municipality should hesitate to adopt measures to safeguard the interests of taxpayers, but "penny wise and pound foolish" is the prevailing policy, and, as our forefathers did so do we, though financial methods and conditions have entirely changed. Frequently when an issue of bonds is proposed and the question of having it "certified" is under consideration, a local financial institution will offer to place its signature on the back of the bonds attesting their genuineness, and the argument is advanced that public officials should patronize home industries, etc. On the other hand the trust company which has been most active in directing attention to the need for better methods in the issue of all public obligations insists that "the value of certification lies in the safeguards it attests" and that the mere writing of another name on a bond in no way protects against either over-issues or forgery.

This trust company has backed up the foregoing statement by establishing a protective method for the issue of bonds composed of a rigid system of safeguards, yet so directed as to materially assist municipal officials in the performance of a most difficult duty, relieving them of responsibility and serving their convenience. The method not only protects the investor, but renders a much greater service in safeguarding the interests of the taxpayers-which, of course, should be the chief consideration of officials responsible for the proper issue of bonds.

At various times state authorities have

endeavored to provide official supervision intended to protect bond issues, but so far none of these state-directed plans have been wholly satisfactory, and municipalities situated in states adopting such procedure have had their bonds issued under trust company certification methods in addition to the modus operandi provided by the state. It is unfortunate that municipal officials usually remain in office only for short terms, and therefore cannot familiarize

themselves with the technical details of matters, such as bond issues, which may come up only once or twice during their terms of office. It is encouraging, however, to note that the more experienced officials tend to the employment of safer methods for the issue of their bonds, many cities having adopted the plan of having their bonds certified by trust companies providing effective safeguards covering the process of preparation and issue.

IVIC pride in our modern towns is beginning to show itself in many forms, among which not the least important is a higher standard of illumination. The stores are more brightly lighted than in times past, and the various "White-way" campaigns have improved, to a marked degree, the appearance of the streets.

Along this line, it is only natural that the standard of residence lighting should be raised. As the porch is the part of the house which is most visible from the street, the illuminated porch is an indication that the owner is doing his share, in one respect at least, toward the general attractiveness of the town. Not only is good porch lighting attractive, but it has an element of protection. Burglars and sneak thieves are more likely to pass by a house that has a

porch light burning than one that has not. Most of the advances in the art of illumination have been due to an increase in efficiency of the light sources themselves. This, however, has been paralleled by improvements in the reflectors and other auxiliaries. These changes have made good porch lighting more feasible than ever before, and have placed it within the reach of everyone, no matter how simple his home.

The incandescent lamp is the most logical illuminant for this purpose. A few years ago the lamp most in use for porch lighting had a carbon filament; it consumed 30 or 50 watts of electrical energy, giving 8 to 16 candlepower, respectively. Now, however, we have available the 10-watt Mazda lamp, which gives 8 candle-power. This is

adequate for lighting the average small porch. And think what that means! Assuming the cost of power to be 10 cents per kilowatt hour, this lamp costs but one-tenth of a cent per hour to operate. In other words, the porch can be lighted every night from seven to eleven o'clock for 12 cents per month.

Let us now see what comprises good porch lighting. Of course, some porches are fitted up as a room and used for playing cards or reading at night, in which case they should be lighted in the same manner as a room. Lamps of the size which would be used indoors and similar reflecting devices are applicable. If the ceiling is dark, direct lighting must be used; if light in color, semi-direct or totally indirect units give a very agreeable light and make a pleasing appearance.

The average small porch, however, requires but a very low intensity of general illumination, sufficient for a visitor to see clearly the bell and name-plate, and to be distinguished from within the entrance. The steps must be well lighted to avoid danger from accident. As stated above, it is desirable that the wattage or the size of the lamp should be very small, for it is advantageous to have the porch light burning all evening. For reading purposes, it is desirable to have a weatherproof flush receptacle provided in addition to the ceiling light, so that a portable lamp may be connected to the lighting circuit.

The logical location for the porch light is at the ceiling, either midway between the door and the steps, or, in some special instances, at the front, above the steps.

Formerly the standard equipment consisted of a metal ceiling ring, holding a clear spherical glass ball, etched on the inner surface. This globe absorbed a certain percentage of the light, depending on the depth of the etching, was not attractive, and lacked diffusion.

By diffusion we mean a breaking up or spreading of the light rays-a soft light in contrast to a glaring one. This is roughly shown in Fig. 1. At the left is a clear, bare lamp, the filament visible in its full brilliancy. At the center the lamp is inclosed in one of these roughed inside globes just described. Partial diffusion is produced.

592

『《་ཀ་༤ཐམ་

FIG. 2