from "built"). Obviously, when the purchaser departs from the broad market thus established for a given commodity, he immediately sacrifices the economy offered thereby.

12. Individual opinions may differ as to the advisability of requiring for Government purposes special features not included in standard commercial apparatus, at special prices. Standard specifications iron out" all this individuality and reduce the purchase of a certain class of apparatus to the most practical basis. This feature may be illustrated by the problem of operating a horse-car system samples of which may be found in New York City, Santa Rosa, Cal., and doubtless other places with which the writer is not familiar. The individual opinions of certain of the drivers and passengers, prompted by humane or artistic motives, might call for horses of not to exceed a certain age and capable of showing a speed, detached from the car, which would necessitate the horse having close relations in and about the celebrated "blue grass region" of Kentucky: but, the governing conditions of revenue and operating expenses, makes it necessary for the management to turn a deaf ear to the aforesaid opinions, and buy large quantities of animals which possess the requisite amount of stability, in a market which is broad and dependable and which will yield renewals in any quantity without disturbing the market price.

13. So with industrial motors for operating the general classes of machinery. A broad market has been established for this class of motors, and greater economy of operation will result from the purchase of good commercial motors and the renewal of the same from this market as required, than could possibly be obtained from the purchase of special motors with special operating characteristics and details of construction.

14. A point that is often lost sight of is the question of "reliability." This quality is bound to be possessed by apparatus which is successfully marketed in large quantities. It is very liable to be lacking in special apparatus. It is regrettable that this quality can not be given definite valuation and recognition in specifications, for as insurance of continuity of service, especially in cases where the product of the machine is relatively many times more valuable than the motor operating it, it ranks far beyond efficiency and other characteristics which are usually given great prominence in specifications.

15. Obviously, great elasticity is necessary in standard specifications to enable the market conditions to be taken advantage of to the fullest extent. The usefulness of the American Institute of Electrical Engineers standardization rules in this respect has been favorably commented upon by Mr. Scott.

16. The application of this quality is aptly illustrated in the steering gear of an automobile. Almost everyone has at times noticed the apparently loose and aimless way in which the front wheels of an automobile wobble about when travelling along an uneven road at slow speed. This would at first appear a poor mechan

ical job, but experience has taught that in order to remove the strain from the driver's hands and the steering gear parts, this amount of elasticity and freedom is necessary. The thousands of cars in daily operation with this apparently loose-jointed steering arrangement is proof of its efficacy.

17. I quote the following from Mr. Scott's paper: "Obviously, it is impossible for the Government to use standard specifications if there are no standards." As set forth at the beginning of these comments, the Government has required specifications of some sort or other for every purchase of electrical apparatus which has been The Government early recognized the value of the application of electricity and has been a heavy purchaser of electrical apparatus from the first. The development of the art was rapid and, consequently, the specifications issued by the various departments required frequent revision to keep pace with the development. The number of necessary revisions multiplied by the number of departments issuing specifications make “an average of one in about every twenty-two months" appear quite reasonable.

18. While certain classes of electrical apparatus have been developed for several years to the point where standardization among manufacturers was possible, it was not until 1908 that the motor manufacturers organized and adopted definite standards. The Government's standard specifications for lamps were issued prior to that date, and the Navy Department's standard motor specifications a year later. (The Navy Department has for years issued standard specifications covering various classes of materials for naval purposes. These are revised from time to time as required, and they have done much toward establishing desirable standards. and preventing undesirable specialization. There are upwards of 700 of these Navy standard specifications in force at present.) While the adoption of standard specifications for other classes of electrical apparatus might have been undertaken somewhat earlier, the present activity in that direction is not long delayed, and bids fair to keep conservatively in touch with the development of the apparatus itself.

19. The material designated above as Class II, which is experimental, or the application of which is restricted to special cases, must necessarily still be covered by specifications which can not be called "standard." Under this class comes electrical apparatus for use on naval vessels. The extreme importance of military preparedness and the special atmospheric and temperature conditions surrounding this apparatus, together with the rugged character of the same necessary to withstand the abuse of the service, places this material in a class by itself. Some of this apparatus could be well supplied from the commercial market, but it is difficult to segregate it.

As shown by Mr. Scott's "example of the non-conformity of specifications and lack of coöperation" in apparatus installed in the same compartment, it is evident that the work of standardization

of motor specifications for navy yard use, directed by the Secretary of the Navy, can well be extended toward the unification of the requirements of apparatus for naval vessels.

20. The only method by which specifications for standard apparatus can be made sufficiently comprehensive to fulfill their purpose in accordance with the foregoing, is by full and free coöperation among the departments which will use these specifications, and the same degree of coöperation between the Government representatives and the manufacturers. The result will be in the nature of a liberal compromise of unimportant features and the adjustment of the more important features to meet the demands of good engineering and the manufacturing requirements involved. The pressure of the specifications should only be felt in the vicinity of obviously inferior apparatus. The same methods should obtain to as great a degree as possible in the preparation of specifications which can not be made standard. The value of coöperation with the manufacturers can not be over-estimated, and both the Government and the manufacturers are to be congratulated upon the cheerful and friendly spirit which has prevailed at recent conferences between their representatives with regard to the requirements for Government apparatus.

Dam No. 10, Monongahela River, Damaged by Burning Oil**

An oil pipe burst at the pump station of the Eureka Pipe Line Company, located just above Lock No. 10, and considerable oil leaked into the river when the water in Pool 10 was drawn below the crest of the dam. At about 2 p. m. on October 29th, when the wind had collected the oil in the corner above the abutment end of the dam and the waves had deposited a quantity of the thickened oil on the top of the dam, some one set the oil on fire. The heat from the burning oil was so intense as to completely destroy the mortar finish on top of the dam, which was about 21⁄2 inches thick, for a distance of 50 feet by breaking the bond between the mortar and the concrete, and the mortar into small pieces. The mortar cracked with such force as to produce loud reports and to throw chips to a distance of about 75 feet.

*Report by United States Assistant Engineer J. L. Callard.

COMPARATIVE TESTS OF WYE AND DUMPY LEVELS

BY

Lieut. JAMES G. STEESE
Corps of Engineers

The question having arisen at the Engineer Depot, United States Army, as to the advisability of changing the type of engineer's level used by engineer troops in the field and on construction work in the Engineer Department at Large, comparative test-runs were made in September and October, 1910, of levels of the Dumpy and Wye types. By the use of the dumpy level more generally, satisfactory service was expected and, in addition, there would be a saving of about 20 per cent in first cost of instruments.

For the test runs a Buff and Buff wye level No. 7196, 18-inch telescope, cost $126.00, and a Buff and Buff dumpy level No. 7072, 18-inch telescope, cost $91.00, were used, both instruments being

new.

The runs were made at various times during a period of about a month, in a bright sun and heavy wind, and also on cloudy, damp days. The instruments were carefully adjusted the first day, and no further adjustments were made.

The table below shows in detail the results obtained. In figuring the allowable error of closure of each circuit, I have used the formula

E=0.02VD

where E allowable error in feet

and D-length of circuit in miles.

This formula is the usual standard for precise levels in the United States Engineer Department with a precise levelling instrument. We have used the same formula for our check levels on the Panama Railroad Relocation, using an ordinary engineer's wye level.

The "A" runs were made at the depot, upon comparatively level ground. Maximum sights of 250 feet were taken; all back and fore sights were balanced by pacing. Self-reading rods were used and the thousandths were estimated by the instrument man. On this part of the work I was assisted by Lieutenants North and

Lyman, Corps of Engineers, each of whom ran two circuits with each instrument.

The "B" runs were made in the field, near Congress Heights, D. C., on rough ground covered with brush, approximating working conditions. The sights varied from 50 to 300 feet, and were practically balanced; the rod was read to hundredths.

All runs were closed on the starting point.

There is no difference in speed between the two instruments. The dumpy level is more compact, lighter, and simpler to work with. From its solid and substantial construction, it would seem almost impossible to injure it by any ordinary blow or fall. Abuse or a bad accident would, of course, render either instrument valueless. To check the adjustment of the dumpy level by the peg method requires more time than to adjust the wye level, but the adjustments once made would be retained under rougher handling, and for a longer time.

To develop the relative accuracy under continued use would require more extended tests, but the above results show the dumpy level to be capable of greater accuracy than is ordinarily required, and it is believed that the dumpy level is the safer instrument to use on miscellaneous work, especially on construction; the Wye level being reserved for establishing long bench lines.