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their unsightly proportions always produce a bad impression, and in place ofadding to the beauty of a landscape, often spoil the effect of the finest scenery.Indeed, it appears that this branch of architecture has thus far been entirelydeprived of all chances of making a display of the beautiful and ornamental.The gloomy aspect presented by the interior of some of those very large struc-tures involuntarily reminds us of a tunnel, with this difference, that the latter iscool and clean in summer, while in the former the air is dusty and suffocating.To these objections an open bridge is not liable.

To insure the durability of the timber to be used for the floor of the projectedwork, it should be well seasoned before it is put in. The beams, winch formthe most important part of the floor, will have to be planed on all sides and thenreceive two coats of boiled linseed oil and Spanish brown, which, next to redlead, is the most durable of paints, and also the cheapest. All parts of the rail-ings, as far as exposed, will be well painted. The floor will be crownedsufficiently for rapid draining. The first course of plank will be laid close andtight, and covered with a thick wash of newly slacked lime, upon which thesecond course is laid. The joints of the upper floor should be pitched. Thelime between the two floors cannot wash out, and will effectually prevent rottingbetween the two courses. Whenever the upper course of plank is worn outand renewed, another coat of lime should be put on. If preserved in this man-ner, no fear need be entertained, that the timber will suffer from early decay.The tops of the beams will be particularly well painted, and as these timbersare exposed all around to a free draft, they will last as long as timber can last.The upper floor will wear out before it could be affected by the rot: it will bearranged so, that it will form an entire smooth surface, crowned in the centre, andsloping off on both sides, for the discharge of the rain through the openings inthe side railings. No opening whatever or offset will be left in the floor wherewet or dirt could collect and cause a rot. As the wind will have a fair sweepover it, its action will assist much in the cleaning, which should, from time totime, take place.

9, GRADING.

The practicability of attaining an elevation of 121 feet above low water, aheight sufficient to clear the largest steamboats in all navigable stages of water,will be doubted by many, who will refuse to investigate the few simple data,upon which it depends. The levels of both banks of the river have been takenby Mr. Rickey and myself, sufficiently accurate for our present purpose.

It was stated in the fore part of this report, that the flood-mark of 1832 is 63feet above low water. Now the curb-stone at the lower corner of Front andMain street is 59 feet above low water, or 4 feet below high water. From thislevel the grading of the bridge commences, and continues at the rate of 4 1-2degrees, or 7.75 feet rise per 100 feet distance, to the centre of the abutment, adistance of 272 feet, when an elevation is attained of 80 feet above low water.The grading of the wharf at this point is 45 feet above low water, and therefore35 feet below the floor of the abutment, and 14 feet below the curb-stone at thecorner of Front and Main. While the wharf, therefore, descends 14 feet, theapproach of the bridge rises 21 feet. A rise of 4 1-2 degrees will not be consid-ered objectionable where one is accustomed to very steep gradients. To afforda comparison, I will observe here, that the pavement of the wharf below theabutment, drops at the rate of 9 1-2 degrees. The graded wharf on the Coving-