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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1860 Excerpt:...is on shore with a sandy or muddy bottom, it is well not to work the engines too long with a view to start her, for all propellers stir up the sand, &c. If a ship do not start with the first few turns of the engines, there is not much chance of their effecting it. 202. The Snifting-valve "drawing Air." On first getting up the steam, and attempting to get a vacuum in the condenser, it is sometimes found that the snifting-valve is " drawing air," as it is termed; that is to say, from the valve not fitting tight, air is making its way by these means into the condenser. This is liable to happen from a piece of chip or coal, or a piece of seaweed, having passed into the condenser, and becoming jammed under the valve, which allows air to pass in and destroy the vacuum under-the air-pump bucket. It is usually remedied by a bucket of water being poured on the valve. If this be repeated two or three times, it will generally clear it. Sometimes a piece of oakum will get under the valve, which is generally the source of great trouble; for it is apt to wind itself round the spindle, and the water will not be able to wash it away. The consequences of. air getting into the engine through the snifting-valve have proved to be more serious than could at first sight be imagined. The snifting-valve not being closed, we shall in many engines have a pressure of air against one side of the foot-valve; and the injection-water producing a vacuum in the condenser, that valve will not open on the up-stroke of the air-pump, and the water not being pumped off will rapidly accumulate in the condenser, and at length find its way into-the cylinder; and consequently the engine will, in all probability, be broken down. Such an accumulated catastrophe, arising from s...