machinery, and hold spaces, so as to give the important advantage of increased cargo accommodation obtainable from the use of their improved machinery, which occupies considerably less space than the engines and boilers of the same power which have been replaced. The new engines are of the triple expansion type, and the boilers, which are designed for supplying steam of 150 lb. pressure, are worked on Howden's system of forced draught, which combines increased power with high economy in fuel. The object of the owners in refitting the Ohio was to test the capability and economy of this system of forced draught on a sufficient scale to guide them in dealing with steamships of the largest class and great power.

In the refit of the Ohio the boilers were designed to work with a very moderate air pressure, this being sufficient for the power required by the contract. The combined power and economy, however, guaranteed by Messrs. Howden & Co. for the use of their system of forced draught was higher than has hitherto been attempted in any steamship, and sufficient, if attained, to prove the large reduction that could safely be made in the number and size of boilers for the use of the system, and the quantity of coal required to produce a given power. The contract for the refit of the steamer required that 2,100 indicated horse power (which was the maximum power of the engines removed) should be maintained during the trial on a consumption of 1.25 lb. of coal per indicated horse power per hour. Originally the boilers of the Ohio, from which this power was produced, were three in number, double ended, 12 ft. 6 in. in diameter by 17 ft. 6 in. in length, having each six furnaces 3 ft. in diameter, or eighteen furnaces in all, with an aggregate fire grate area of 300 square feet. The new boilers, fitted with the forced draught, are likewise three in number, but single ended, 13 ft. in diameter by 11 ft. 2 in. in length, having each three furnaces 3 ft. 3 in. in diameter, or nine furnaces in all, with an aggregate fire grate area of 112 square feet. Air for combustion is supplied to the boilers by one of Messrs. W.H. Allen & Co.'s fans, 5 ft. 6 in. in diameter, driven direct by an engine having a cylinder 7 in. in diameter with stroke of 4 in. The boilers removed had two stoke holds across the ship, one fore and one aft of the boilers, while the new boilers have only one stoke hold on the after side. The engines removed have cylinders 57 in. and 90 in. in diameter by 48 in. stroke, while the new engines have three cylinders 31 in., 46 in., and 72 in. in diameter respectively, with piston stroke of 51 in.

During the trials the coals were weighed out under the supervision of the officers of the company, who also took the record of speed and other data. After running down Channel for a considerable time, the trial on the coals weighed out began, and lasted 4 hours 10 minutes, during which time 10,885 lb. of Welsh coal were burned, the trial ending with the same revolutions of engines and the same pressure in boilers with which it began. The mean indicated horse power, calculated from the mean of seven sets of indicator cards, taken during the trial, and the mean revolutions per minute, found by dividing the total revolutions recorded on the engine counter by the minutes in the period of the trial, amounted to 2,124, thus making the consumption 1.23 lb. per indicated horse power per hour, and the power per square foot of fire grate almost exactly 19 indicated horse power. While testing the indicated horse power and consumption of coal, the steamer ran to and fro between the Cloch and Cumbrae lights, and also made several runs on the measured mile at Skelmorlie, from which the mean speed of the vessel was found to be 14.12 knots per hour. The remarkably high results obtained were most satisfactory to the representatives of the owners, and a large party of experts on board congratulated Mr. Howden on the successful fulfillment of the onerous guarantees undertaken.—Engineering.

THE CEARA HARBOR WORKS.

The works illustrated by the engravings are now being constructed under a concession from the imperial government of Brazil. The province of Ceara has an area of about 50,000 square miles, and is one of the richest in Brazil. Its produce comprises sugar, coffee, cocoa, cotton, tobacco, spices, fruit, cabinet and dye woods, India rubber, etc. Its population at the last census, taken in 1877, amounted to 952,624 inhabitants, that of the capital, the city and port of Ceara, being about 40,000. Although Ceara is the principal seaport at which lines of English, French, American, Brazilian, and other steamers regularly call, prior to the commencement of the harbor improvements it was almost an open roadstead, passengers and goods having to be conveyed by lighters and boats between vessels and the shore. The official statistics of the trade and shipping of the port show that an income of £35,750 per annum will be collected by the Ceara harbor corporation from the dues which they are authorized by their concession to charge on all imports and exports and on the vessels using the port and from the rent of the bonded warehouses.

NEW HARBOR WORKS, CEARA, BRAZIL.

The drawings given here show the nature of the works, which are of a simple character. The depth of water along the principal quay, which is being constructed of solid concrete, and is connected with the shore by an iron and steel viaduct over 750 ft. in length—which is already completed—will be 19 ft. at low water and 25 ft. at high. This quay and breakwater is shown in perspective, in plan, and in section, and is of a very heavy section, as will be gathered by the scale given immediately below it. Meanwhile the landing of cargo is temporarily carried on at the end of the viaduct, which at high tide has a depth of about 20 ft. of water. The custom house and bonded warehouses are being built of the fine granite obtained at the Monguba quarries, which adjoin the Baturite railway, about sixteen miles from the port. A new incline has also been constructed from the rail way down to the port. The line has been laid along the viaduct, and will be extended over the quays as soon as they are completed. The concrete, of which a large quantity is being used, is mixed by Carey & Latham's patent mixers, and the contractors have supplied the very large and complete plant for carrying out the operations.

The engineer to the corporation is Mr. R.E. Wilson, M. Inst. C.E., Westminster, and his resident at Ceara is Mr. R.T.H. Saunders, M. Inst. C.E. The contractors for the work are Messrs. Punchard, McTaggart & Co., their representative at Ceara being Mr. George Wilson, M. Inst. C.E.—The Engineer.

ELECTRIC STREET RAILROADS.

By GEORGE W. MANSFIELD.

Why should we prefer electricity as the propelling agent of our street cars over all other known methods? I answer, without hesitation, because it is the best, and being the best is the cheapest. Briefly I will present the grounds upon which I take my stand.

To-day the only methods for tramway service are three in number: Horses, with a history of fifty years and over; cables, with a history of fifteen years; and electricity, with a history of two years. I give the latter two years on the basis of the oldest electric street railroad in existence to-day, and that is the Baltimore railroad, equipped with the Daft system.

The main points for consideration common to each are six in number:

• 1st. Obtaining of franchise.
• 2d. Construction of buildings, viz., engine house or stable.
• 3d. Equipment—rolling stock, horses, engines and dynamos.
• 4th. Construction of tramway.
• 5th. Cost of operation.