be made 4 inches d would be 1.677 inches, or, k may be 3.354 inches, and d equal 2 inches, etc. To provide for curvature and normal refraction, not allowed for in Equation 5, the foot of the pendant F' will not bear directly on line PT, but at F" against another straight line PT' rigidly attached to line PT and making a slight angle with it. Equation 5 also assumes R to be the inclined distance from the instrument to the target, which, in the case in hand, is greater than the horizontal range by 4.6 yards in 800 yards; 1.4 yards in 2,600 yards, and 0.8 yard in 4,400 yards. This could be corrected by having the pendant not of constant length, but telescoping so that its foot would travel only horizontally. Tide would then be corrected for by raising or lowering the contact of the foot of the pendant in the shoe or slide, which latter would traverse the line or rod PT only horizontally. The advantages of this straight line plan would be the ease of manufacture and the fact that sliding contact could be surfaces of material width. The bearing at T would be a vertical cylinder journaled above and below and with one side of middle portion cut away in a rectangular notch reaching past its axis, in which notch the rod PT would slide. But the disadvantages are that the point T would be difficult to adjust with sufficient precision, and that there would be a varying deflection in rod P T and in guide A P. And these disadvantages are so great that the substantial curved faced plotting arm with its constant rigid backing, though requiring patient, skillful handwork in its making, would be far more satisfactory in practice. THE CHESAPEAKE AND DELAWARE CANAL IN THE CIVIL WAR BY Maj. R. R. RAYMOND During a very interesting lecture upon a totally different subject, the lecturer told of a magnificent masonry lock which had been constructed by the Government at considerable expense, and yet through which only one vessel passed each way daily. To him it appeared that Uncle Sam was extremely generous to the owners of this vessel. He passed on to other matters, leaving in the minds of his audience a distinct impression that the people had been forced to pay a large sum for the benefit of a few individuals, and that if only his wisdom had been possessed by the Government engineers, this wrongful waste would not have occurred. The lecturer was an able minister of the Gospel and therefore well qualified to pass upon problems in engineering and commerce. There is a proverb that "They also serve who only stand and wait;" at least, that is the substance of it. The mere existence of that lock, standing there practically idle, but ready at any time to serve, was doubtless saving the people countless thousands of dollars day after day through its effect upon freight rates of other systems of transportation in the same section of the country. The purpose of this very brief article is to suggest that the true value of a waterway is not always apparent, and to unearth an interesting bit of history which tends to show that even the military importance of such a highway is not invariably appreciated. There is a small canal cutting through the backbone of the peninsula between Delaware and Chesapeake bays; its channel is of small dimensions and its length is less than 14 miles. A great majority of the people of the United States are unaware of its existence. High authorities have pronounced it to be of little military or naval importance; and yet someone must have recog nized the urgency for such a canal, else the herculean task of cutting such a great ditch through a ridge 100 feet high, by means of the primitive hand methods of a century ago, would hardly have been undertaken, nor would the Government and three States have contributed two and a quarter millions for the work. In 1906, Capt. Phillip Reybold made an address on this canal at Wilmington, Del., and the following extract from his remarks sheds some light upon the matter: "On the 24th day of August, 1814, the battle of Bladensburg was fought, and the British, under General Ross and Admiral Cockburn, captured Washington, burning the Capitol, White House, and all the public buildings. The American people do not want that repeated. It was this disaster that resulted in the building of the Chesapeake and Delaware Canal, and that is why the Government contributed $450,000 toward its construction. * # The canal was completed in 1829, but as railroads were constructed and constantly improved its importance became overshadowed, and when the War of the Rebellion broke out it had been apparently completely forgotten by the military authorities at Washington. It was Captain Reybold's father, Capt. Anthony Reybold, who, being a maritime man, was well acquainted with the canal, and who, meeting by the merest chance and at the psychological moment an agent of the Federal Government, suggested at a time of great peril to the country the use of the canal so graphically described by Captain Reybold in the address mentioned above and quoted below: "On Wednesday the 17th day of April (1861), Virginia seceded from the Union and was starting her troops north to go to Washington. There was not a handful of troops in that city nor a breastwork thrown up, and the Federal Government started its troops south. You know what happened in Baltimore on Friday, the 19th of April, as the Sixth Massachusetts passed through, and that night every bridge on the Philadelphia, Baltimore, and Washington Railroad was burned from Baltimore to the Susquehanna River and totally destroyed, and the Federal Government had absolutely no means of transporting troops along the seaboard by rail to Washington; in fact, all land communication was severed. "On Saturday, the 20th, the Government seized all the propeller steamers in Philadelphia that could pass through the Chesapeake and Delaware Canal, and how well I remember that Saturday night as they steamed down the Delaware River and passed through the canal, and before daylight in the morning they were at Perryville, and just as the sun was peeping up over the horizon the trains arrived at Perryville with the troops, where they were rushed on board of steamers and hurried away down the Chesapeake to Annapolis and by way of Annapolis Junction to Washington, and when that body of troops arrived at the Capital the Confederate outposts were at the Virginia end of the Long Bridge, and for the next sixty days this Chesapeake and Delaware Canal was the key to the whole Federal situation. The Potomac was closed by a series of batteries from Aquia Creek to its mouth and its waters were patrolled by a steamer called the Page, which the Confederates had converted into a gunboat. Suppose there had been no canal, what then would have happened? You would never have heard the cry of 'All quiet on the Potomac' going up, although you might have heard the cry of All quiet on the Delaware;' and the blood that soaked into Virginia soil would have been poured out in Pennsylvania and New Jersey. and reconstruction would have taken place in the North instead of the South.' Throughout the war this canal played an important, even a vital, part. Over it were transported reenforcements, food, clothes, ammunition and other stores, without which the Army of the Potomac could hardly have kept the field; and hospital boats carried back to the North wounded men who could have been moved in no other way. Would it not seem that the name of this canal deserves a better fate than oblivion? Yet the suggestion is sometimes made that because it can not, with its present small cross-section and the necessity for charging tolls to maintain it, compete with the great coastwise rail lines and earn dividends, its construction was a mistake and its price wasted. FUEL OIL V. COAL BY Mr. S. E. LAWRENCE COMPARATIVE COSTS FOR EQUAL EFFICIENCY The oils on the Texas market and those available for use in this section, along the coast, are drawn from the Beaumont Humble, Spindle Top, Caddo, and other more local fields and from the Oklahoma districts as well. The latter, delivered here via pipe line, represent a mixture of most of the classes produced in that section, oils of both paraffin and asphalt bases being mixed with reduced crude in smaller quantities. The pure paraffin base oils in this mixture represent, usually, 10 per cent or less of the total, and the paraffin characteristics are largely lost in the much larger percentage of the prevailing asphalt base. The local fields contributing to the supply for this market are the Goose Creek and Hoskin's Mound wells. The former has proved itself hardly worthy of consideration. The oil produced, while of a fair grade when separated, gives poor results from a heat producing standpoint, because of its inclination to hold water in suspension longer than other oils experimented with; it also contains much foreign matter. The Hoskin's Mound product, while limited in quantity, is easy of access for certain plants and represents an ideal fuel, giving better practical results, considering all the desirable points, than any other oil used. This oil, being much clearer and freer from trash and sediment than the average oil, presents a distinctive greenish iridescence and has more the consistency and physical appearance of an engine oil than a crude product. It left very slight deposits of ash in the tubes when burned, this deposit differing from the ordinary soot in that it was much lighter in color and more easily removed from the tubes than the ordinary soot. this oil was less rich in the more volatile hydrocarbons, its steamproducing power was not impaired; on the contrary, it was higher, |