rolling motion, the theory being, of course, that the centre of the ship must necessarily be the spot in which the motion is the least. Another peculiarity of the Guion steamers is, that they have their saloons upon the upper deck, with the cabins directly communicating with them. This is an arrangement which is greatly esteemed by passengers, especially those who are not able to feel themselves quite so comfortable on board ship as persons bred to the sea. The two latest additions to the Guion Line, the Montana and Dakota, have made some very fast passages, the average time of their runs being close up to the crack passages of the Cunard, Inman, and White Star liners.

The Guion Company with its fleet of eight powerful vessels maintains a weekly passenger service between Liverpool and New York, the steamers leaving Liverpool every Wednesday and New York every Tuesday. It was, we believe, the design of the company at once to establish a bi-weekly service, but the unfortunate depression which has fallen upon the American trade has caused the temporary postponement of this project. It is, however, tolerably certain that upon the first renewal of trade the Guion Company will further develop its resources, and helped as it is by very powerful connections upon the other side of the Atlantic, it will have the fairest chances of success. The company has the prestige belonging to the carriers of the United States' mails, and until recently were the only recognised American owned steamship line in this country. Commencing their career in 1866, the Guion Company have in the comparatively short space of nine years taken a place in the first rank of the steamship companies of Liverpool.

It has been already remarked that the Guion Company had a splendid advantage in their passenger organisation and connections coming down from the old sailing ship times, and it is at this day remarkable for the number of steerage passengers it carries. From first to last, during the career of the company as a steamship company, not less than 300,000 passengers have been carried, and it is a remarkable testimony to the character of the vessels and the splendid management of the line, that there has been no loss of life from accident. The great strength and solidity of the steamships form a guarantee against disasters of the ordinary kind; but these features do not militate against the speed of the vessels which frequently make the passage under the 10 days' limit. The chief feature of the Guion Company's management is native pluck and energy, and it would be difficult indeed to find anywhere a gentleman more able, experienced, and efficient than Mr. Ramsden, in whose hands the management of the passenger department has so long been placed.

DIRECT-ACTING SPRING SAFETY-VALVES.

ON PROPORTIONING THE HEAD OF VALVE TO OVERCOME THE INCREASING RESISTANCE OF THE SPRING.

" square steel 2" inside diameter

AKE a 3′′ valve, 85 lbs. pressure; load 600 lbs. This
corresponds to a spring of
13 coils, and 11" long. This spring deflects 1" with its
load on it, and as the valve is required to liftth of its

=

diameter-viz., ", it is evident that 75 lbs. equal the force necessary to be applied on the head of valve in order to keep it up from its seat; and as 12 lbs. is the force per " on the head at the instant of closing, 7 6.25 square inches equal the area of the concentric head, on which the steam acts and corresponds to 41" diameter. But sometimes the pressure on head of valves falls to 9lbs., and 35 = 8.333 square inches equal area of head of valve.

=

ON THE PROPORTIONS OF AREA OF SEATING AND STRICTURE ORIFICES.

Let 0 opening at narrowest part of seating orifice, and

O

0'

Let R

R'

=

=

opening at narrowest part of stricture orifice.
relative volume of internal pressure, and

relative volume of steam in concentric chamber.

Let V = velocity of steam due to internal pressure, and velocity of steam in concentric chamber.

V' =

Let R" relation of circumference to diameter.

Let r

=

= area of seating orifice, and

r = proportion of area of stricture to seating orifice, and

a

= area of stricture orifice.

These proportions are the secret and soul of the valve. Let them be disturbed either by increase or decrease, and the efficiency of the valve will fall; and such is the condition to which this valve has been brought, that when applied as the Board of Trade rule prescribes, the valve will rise at 60 lbs., admit of no accumulation, and close again at 60 lbs., the

same pressure at which it rose. I cannot make it speak, but I can make it play beautiful rythmic music. "Make me free in the seating, and about the spindle, poise me true on my centre," says the valve, "and as the steam rushes from imprisonment in the boiler to enjoy the freedom of air at the top of the waste pipe, winding its spiral and wave-like motion through my double orifice, you will hear my melodious voice singing the song of molecular freedom." Indifferent must be the man; cold the heart, and dead must be the soul of him who could not admire the grandeur of the structural "idea" of this valve.

And now, Mr. Editor, as I pass from my own valve to that of other valve mechanism, let me say a few words of gratitude. To the mental intrepidity of that most unwearied of all Government officials, Mr. Thomas Gray, I am indebted for the wisdom of his councils and the kindness of his words, always bringing encouragement in their train. From first to last they have stimulated me to produce the valve in its present state of perfection. Shipowners also are indebted to him for the sagacity he displayed by the rapid manner in which he adopted a new and novel design, conferring a large benefit on steamship owners; and to the chief surveyor, for he also granted my very first request. To yourself, also, Mr. Editor, are we all indebted, for you were early in the field with your offer of £100 prize, stimulating the inventive faculty of the country to produce a safety-valve, which would help, in some degree, the depressed state of the shipping interest; although, owing to a small mishap of the fitter, I did not get your prize, a burr on the spindle produced by the key which receives the padlock, being driven in from the wrong side of the taper, thereby creating friction on the spindle, by burring up the top edge of the key way, and preventing the valve from rising and falling freely. This it was which made the arbitrators say something was sticking inside; but I was confident I had the best valve, because no living man had reasoned the subject in the same philosophical spirit, and that the trade of the country would fall into my hands.

THE SAFETY-VALVE AS IT OUGHT TO BE LOOKED AT BY THE BOARD OF TRADE.

No pair of ordinary safety-valves, at or about 60 lbs. pressure, of the dimensions prescribed by the Board of Trade rule, and loaded direct by a spring of the necessary strength to secure safety, will carry away all the steam generated by the fires, without an accumulation of internal pressure, which materially affects the safety of the boiler. On this point, the shipowner can sit in his easy-chair, for the whole responsibility of fixing the limits of pressure in the boiler is thrown by the

Legislature on the Board of Trade; and its anxiety and care for the safety of the public, demand that it should know the exact nature of that responsibility. For that purpose, it must know the conditions of construction and quality of material of which the boiler is made. It can then tell what pressure that boiler can carry with safety, and it generally assigns that pressure; and it purchases from the builder the responsibility of the safety of that boiler. The bargain is a fair and legitimate one on both sides. But if, after having got the responsibility fairly strapped down on the Board of Trade's shoulders, he (the builder) turns round and asks for 10 per cent. of accumulation, he pilfers from the Board of Trade "till," he takes that which is not his own, and for which he never made fair bargain. The scales no longer stand in the state of the balance, and he is no longer a just man of business, for he has given light weight to the Board of Trade. He has no more right to take 10 per cent. of accumulation of pressure than the grocer has to give 14 ozs. for 1 lb. avoirdupois. The behaviour of the two is identical, and were I the Board of Trade, I would not grant one ounce of accumulation of pressure. For, so long as there is a given pressure assigned, and given strength of boiler to withstand that pressure with safety, so long will the position of the Board of Trade on the one hand, and the builder of the boiler on the other, be clearly defined. But let accumulation be given or taken, and both parties have entered on the region of chance, where all is uncertainty.

ON THE SAFETY-VALVE AS IT OUGHT TO BE LOOKED AT BY A
STEAMSHIP OWNER.

Supposing the Board of Trade to allow no accumulation of pressure, or 10 per cent. of accumulation, so imperfect has the safety-valve been, that none would pass the test, even at the latter quotation, when loaded by a spring of the proper strength. But in order to pass muster with the surveyor, some engineers apply a very broad-faced valve (face broad) in order that when the valve lifts from its seat the steam will act on this broad face and help it up against the increasing resistance of the spring, and so keep the accumulation below the 10 per cent. at present allowed by the Board of Trade. (I say at present, because I trust it is only provisional on the part of the Board of Trade.) This is a most heartless valve-heartless, because it is made utterly regardless of the interest of the shipowner. This valve may just save its bones by having an accumulation of only 8 or 9 per cent., but it will lower the pressure in the boiler 16 lbs., or 26.7 per cent., when blowing off at 60 lbs., lowering the water in the gauge-glass about 2 inches before it will close; and between the time of opening and closing, a ton weight of coal has been

D

blown out at the waste-pipe and lost to the shipowner. The valve is shown on its seat at Fig. 14.

Take for example a double-ended boiler 24 feet long and 13 feet diameter.

Let the chord of the arc formed by the junction of the water and steam space be 12 feet. Let the engines be suddenly stopped and the valve blow off at 60 lbs. It will reduce the pressure 16 lbs., or to 44 lbs. when it comes to its seat, and during this time the water in the boiler will have fallen 24"; and since 1 lb. of coal evaporates about 8 lbs. of water, it follows that the number of pounds of water lost in the boiler, divided by 8, will represent the number of pounds of coal blown out at the waste pipe. With the dimensions we have selected it will stand thus, taking 62 lbs. of water to the cubic foot :

24 x 12 x 21

12

54 × 62
8

= 418.5 lbs. of coal blown from one boiler.

If there be 4 pieces of boiler on board ship, then 418.5 x 4 = 1674 lbs. of coal is lost every time this type of valve rises from its seat. But this is not its worst phase on board ship. Supposing one or more of these valves to blow off when a ship has just got under way leaving England and bound for China, this valve would blow continuously to the end of the voyage, unless the engineer let his steam down to, or below 44 lbs. Nor have I gone minutely into its waste of coal, because in lowering from 60 lbs. to 44 lbs. the temperature of the whole body of water in the boiler has been lowered by 16 degrees, and this would add about 500 lbs. more weight of coal blown away every time this valve rose from its seat. It is a thorough "spendthrift ;" but shipowners can prevent it by speci