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boilers, as used on the western waters, is due to the late Oliver Evans . Althoughthis plan is susceptible of great improvements, but little has since his time beenadded. The time, however, is fast approaching when the saving of fuel willbecome an important object. When we add to the first saving of expense offuel, the additional power obtained by a machinery no more expensive, thesaving of time, greater safety of the vessel from fire, reduction of firemen’s wages,greater comfort of a boat where less heat is allowed to waste from the furnacesand boilers,—the aggregate benefit resulting from these improvements willbe astonishing!

But it may be asked, what bearing has all this upon the bridge ? I wouldanswer this question by another:—why object to the bridge on account of thehigh chimneys ? High chimneys are the strongest proofs of defective arrange-ments, they will disappear from our rivers sooner or later, as improvementsadvance. They are objectionable in every aspect;—if they could .be forcedfrom our rivers by some low bridge, it would be the greatest service whichcould be rendered to the navigation of our western waters.

The ostensible object of high chimneys on board of steamers is, to create moredraft. Now, it is fully established, and generally known, that economy in fuelis inversely as the rapidity of combustion. And, on the other hand, the escape oflost heat and unconsumed fuel up the chimneys , is in direct proportion to thedraft. These, and a few more points, are already better understood on oureastern waters, and in ocean navigation, where economy of fuel is a greaterdesideratum than here in the West. Chimneys on eastern boats are muchlower than on western boats; they are still lower on ocean steamers, wherehigh stacks are very objectionable. The question of an increased speed is therenot solved by simply raising the chimneys and increasing the draft, but byother means, a little more creditable to science.

My remarks upon chimneys have extended beyond what was contemplated.But I had to enlarge upon this topic to meet those objections raised against theproject in question, on account of these high chimneys. I am free to maintain,that, in future, the power and value of a boat will be estimated, not by theheight of chimneys, as is now the case, but by their lowness. Low chimneyson a powerful boat will be the best proof of a superior arrangement for the gen-eration of steam. But, as there are a number of boats still running which carryhigh chimneys, and as this fashion is likely to continue for some time yet, weshall be obliged to adopt in the construction of the proposed work, an elevationunnecessarily high. I have assumed an elevation of 121 feet at the centre pieras the maximum to which I can consent.

As an additional comment upon chimneys, I will add, that there is an easymethod of raising and lowering them, which is practiced on most of the oceansteamers, and deserves to be known and applied on our western waters. Apartfrom the passage of bridges, or waste of fuel, high chimneys prove objectionablein other respects. They increase the surface exposed to head-winds, make theboat top-heavy, and are in danger of being knocked off, or becoming entangledamong the branches of trees, when the boat is running near a shore. All theseinconveniences can be avoided by arranging fifteen or twenty feet of the top forsliding. To effect this, the top of the outside, or stationary portion of the chim-ney, is made two to three inches wider than the rest, and its termination armedwith a heavy cast-iron ring, to which four seats are cast for the reception of fourlittle sheaves, which serve for the working of four chains, or wire ropes, for thesupport of the inside or moveable part of the chimney, and at the same time actas guides. Weights are to be attached to the outside portion of the ropes, tobalance the weight of the sliding chimney. A very small force is required to3