1S40.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



253 



"The number of revolutions of the engine per minute is 26, whicli, multi- 

 plied by the spur wheels 55 times, gives that number of turns to the screw 

 for one of the engine. 



26 revolutions of the engine per minute. 

 5J multiple. 



138 revolutions of the screw per minute. 

 8 feet pitch of screw. 



1104 /«■/ tr.-ivelled per minute. 

 20 being i of 60, to bring it into 



22.080 yards per hour, 

 wliirli. (livideil by 1760 (the numljer of yards in a statute mile), gives us 12 

 miles 100 yards per hour as the speed of the screw. Speed of the vessel for 

 26 strokes per minub", 10 1 0-23 miles per hour by the big."— She left Liverpool 

 on the llthult.. for the Isle of Man, and performed the run in theshort space of 

 seven hours and 2') minutes, which is an unusually quick jiassage. The Monn's 

 Isle was fully two hours longer doing the same distance on the same day, 

 starting about half an hoiu' later than the Arrhimciles. The Mona is 10 horses 

 power more than the Archimeilcs, with considerable less tonnage, and draw- 

 ing two feet less water. 



Koi/al Mail Steam Pnci-e(s.— The contract of the " Royal Mall Steam-packet 

 Company " with the commissioners has just been printed, in return to an 

 order of the House of Commons. The company covenant to" keep a sufiicient 

 number (not less than 14) of good and efhcient steani-ves.sels, which shall be 

 able to carry guns of the largest calibre now used on board of steam-vessels 

 of war, supplied with engines of not less than 400 collective horse power, as 

 well as with men, apparel, &C.. and be of at least 1,000 tons burden. One of 

 these vessels is to leave a port in the British Channel twice in every calendar 

 month, ami proceed to Harliadnes. as soon as the mails are on board. Alter 

 an interval not exceeding six hours from her arrival there, she is to proceed 

 to Grenada, and after remaining a time not exceeding 12 hours, go with the 

 mails on board to Santa Cruz, thence to St. Thomas's, thence to Nicola M(de 

 in Hayti. thence to .Santiago de Cuba, and thence to Port Royal in Jamaica. 

 After remaining at Port Royal for an interv.al nut exceeding 24 hours, the 

 vessel, aftpr delivering her mails and receiving others, is to proceed to Savan- 

 nah la Mer. and after a delivery and receipt of mails there, to llavannah in 

 Cuba. After an interval not exceeding 48 hours she is on her return to pro- 

 ceed from Havannah to Savannah la Mer, thence to Port Royal, thence to 

 Santiago de Cuba, thence to Niccda Mole, thence to Samana in Hayti. de- 

 livering and receiving mails at each place, care being taken that she shall 

 always" arrive at Samana, after performing her voyage from Barbadoes, on 

 the 22nd day after the arrival of the mails at Barbadoes from England. 

 From Samana she is to make the best of her way back to England. Imme- 

 diately on the arrival at Barbadoes of every steamer employed under the 

 contract, another of such steam-vessels is to proceed with her mails from 

 Barbadoes successively to Tobago, Demerara, Berbice, and Paramaribo. The 

 period of delay at Paramaribo is not to exceed 48 hours, and then the vessel 

 is to proceed to Berbice, Demerara. Tobago, Grenada, and Barbadoes, always 

 arriving at Barbadoes in time to depart immediately fur Tobago on the arrival 

 of one of tiu> vessels at Barbadoes from England. On the arrival at Grenada 

 of a mail from England, another of the steam-vessels is to proceed from 

 Grenada successively to St. Vincent. St. Lucia, Martinique, Dominica, Guada- 

 loupe, Antigua, Montserrat, Nevis. St. Kitt's, Santa Cruz, Tort(da, .St. 

 Thomas's. St. Juan's (in Puerto Rico), .Samana, Curafoa. Porto Cabello, La 

 Guayra, Trinidad, and thence back to Grenada, so as always to be ready to 

 depart thence with the mails on their arrival from England. Another vessel^ 

 likewise, on the arrival at Grenada of the mails from England, is to proceed' 

 with the mails succes.sively to the Port of Spain (in Trinidad), La Guayra, 

 Porto Cabello, Curafoa, Samana. St. Juan's. St. Thomas'.s, Tortola, Santa 

 Cruz, St. Kitt's, Nevis. Montserrat. Antigua, Guadaloupe, Dominica, Marti- 

 nique, St. Lucia, St. Vincent, and thence back to Grenada, so as to be ready 

 to depart immediately on the arrival of a mail from England. On the arrival 

 of any vessel at Curayoa from Grenada, a sailing vessel is to be ready then 

 to proceed from C'urafoa to Santa Martha, and thence to Carthagena, where 

 she is to remain 24 hours, and then return to Santa Martha and Curafoa. 

 On the arrival of a mail from Kngl.and at Nicola Mole, .another sailing vessel 

 is to proceed thence to the Bahama Islands, and after remaining at New Pro- 

 vidence for not more than 72 hours, return to Nicola Mcde in time to meet the 

 steam-vessel. On the arrival of the mail from England at Port Royal, another 

 steam-vessel is to pmceed thence to C'liagres, Carthagena, Santa Martha, and 

 thence back to Port Royal in time to meet the return vessels from Havannah. 

 On the arrival of the mails from England at Savannah la Mer, another sail- 

 ing vessel is to proceed thence to Trinidad deCuba and Belize (in Honduras), 

 where after remaining 48 hours, she is to return to Savannah la Mer by the 

 same route. On the arrival at Havannah of the mails from England, another 

 steam-vessel is to proceed thence with the mails to Vera Cruz, I'ampico, Mo- 

 bile, or such other port as the commissioners shall determine, returning from 

 the last port to Havannah in time to depart for Vera Cruz immediately on 

 the arrival of the English mail, and another to the Gulf of Mexico, 'Tampico, 

 and Vera Cruz, and then back to Havannah to meet the mails. Another 

 steam-packet, on the arrival of the mails from England at llavannah, is to 

 proceed to Mantanza.? in Cuba, and to New York, stopping at intermediate 

 ports to be named by the commissioners, and thence to Halifax, returning 

 back to Havannah, by the same route on the arrival of the mails from Eng- 

 land. The contract is to commence on the 1st of Decemljer, 1841, or at an 

 earlier period, if mutually agreed, and to continue in force for ten years from 

 the first day on which the first vessel shall put to sea for Barbadoes, and for 

 a longer period, unless determined by twelve months' notice in writing. 



Transmission of the Mails to Nortii America.— The contract entered into about 

 a twelvemonth since for the conveyance of tlie mails by steam-packets of 300 

 horse power and upwards from England to North America vvill come into 

 operation immediately, the Britannia steam-ship having arrived at Liverpool 



to carry out the first mail : she is to be followed by the Arcadia, Caledonia 

 and Columbia, all large and powerful vessels. The terms of the contract are, 

 that the mails shall bo conveyed twice in every month from Liverpool to' 

 Halifax in Nova Scotia, and from Halifax to Boston in the United States, 

 and. « bile the St. La« rence is navigable in smaller steam-vessels, from Pictou 

 in Nova Scotia to Quebec in C^anada. The mails to return by the same route, 

 twice a month to Liverpool. Tlie contract is for seven years certain, and the 

 cimtractor is to he paid for performing this service at the rate of 60,000;. per 

 annum. 



Steam to /lleiandria, Egiipt. — The steam ships Oriental (late the United 

 Slates) and Lieerntol, have been engaged by government to carry the mails 

 between England and Egypt. The Oriental will be ready to s.ail from Fal- 

 mouth for Alexandria on the 1st of August, to be succeeded by the Liverpool, 

 « liich will depart on the 1st of September. These vessels « ill call at Gibral- 

 tar and Malta, in gong and returning; and they are to be only 15 days on 

 the passage to Egypt, and the same time on that b.ack to England. Both 

 ships will, it is expected, sail regularly from and to this port, calling at Fal- 

 mouth to receive ami deliver the mails and passengers ; so that one may 

 shortly take a trip hence direct to Egypt, and behold, in a brief visit, all the 

 wonders of that once glorious land. 



PROGRESS OF RAIIi'lVAYS. 



ATMOSPHERIC RAILWAY. 



We attended on Thursday, the 11th ult., at Wormholt Scrubbs, to witness 

 an experiment on a portion of the Birmingham, Bristol and Thames Junction 

 Railway, which had been laid down by Messrs. Clegg & Sannida, on their 

 patent atmospheric principle ; as might have been expected, the practical 

 introduction of a system so diftereut from that now in use on other railways, 

 excited considerable interest. 



The idea of employing the power of the atmosphere, against a vacuum 

 created in an extended jiipe, laid between the rails, and communicating the 

 moving power thus obtained to propel carriages travelling on a road, we 

 believe originated with Mr. Medhurst, who laid before the public details of 

 his plan in a work he published in 1827, entitled " A New System of Inland 

 Conveyance"; indeed so far back as 1812 he pubUshed some ideas on this 

 method of locomotion. About 1835 some experiments were made with a 

 model in Wigniore Street, by Mr. Pinkus, very similar to those described by 

 IMr. Medhurst ; these experiments, however, failed, from the same cause 

 which probably prevented Mr. Medhurst from carrying his into effect, viz., 

 the impossibility of milking the continuous communication from the inside of 

 the pipe to the carriage tight enough to allow a useful degree of rarefaction 

 to be produced. Messrs. Clegg & Samuda's invention overcomes this diffi- 

 culty in a very simple manner ; indeed the constructing and closing this con- 

 tinuous valve, by henneticatli/ sealing it up with a composition each time a 

 train passes, forms the main feature in their invention. 



The portion of the line selected on which the experiments were made is 

 half a mile long, with a rise of 1 in 120 for rather more than half the dis- 

 tance, and 1 in 115 for the remainder. A continuous cast iron pipe or tube 

 9 inches in diameter, is fixed between the rails, and bolted to the sleepers 

 which carry the rail chairs ; the inside of this pipe, which is unhored, is lined 

 with a strong lubrication of pressed tallow about Jjj of an inch thick, which 

 equalizes the surface, and prevents any unnecessary friction from the passage 

 of the travelling piston through it ; along the upper surface of the pipe is a 

 continuous sUt or groove about IJ inch wide. This groove is covered by a 

 valve extending the whole length of the railway, formed of a strip of leather 

 rivetted between iron plates, the top plates being wider than the groove, and 

 serving to prevent the external air forcing the leather into the pipe when the 

 vacuum its formed within it, and the lower plates fitting into the groove 

 when the valve is shut, makes up the circle of the pipe, and prevents the air 

 entering the tube ; one edge of this valve is securely held down by iron bars 

 fastened by screw bolts to a longitudinal rib cast on the pipes, and thus 

 allows the leather between the plates and the bar to act as a hinge, similar 

 to common pump valves ; the other edge of the valve falls into a groove 

 which contains a composition of bees-wax and tallow ; this composition is 

 soUd at the temperature of the atmosphere, and becomes fluid when heated 

 a few degrees above it. Over this valve is a protecting cover, which serves 

 to preserve it from snow or rain, formed of thin plates of iron about 5 feet 

 long, hinged \fith leather, and the end of each plate underlaps the end of the 

 next in the dbrection of the piston's motion, thus insuring the lifting of each 

 in succession . To the underside of the first carriage in each train is attached 

 the piston ami its apjiurtenances ; about six feet behind the piston, the hori- 

 zontal piston-rod is attached to a connecting arm which passes through the 

 continuous groove in the pipe, and being fixed to the carriage, imparts mo- 

 tion to the train as the tube becomes exhausted of the air ; attached to the 

 piston rod, and preceding the connecting arm, two steel wheels are fixed, 

 which serve to lift the valve to allow the connecting arm to pass, and also 

 for the atmospheric air to impinge immediately on the back of the piston ; 

 another steel wheel, which is attached to the carriage by a spring, serves to 

 ensure the closing of the valve, by running over it immediately after the 

 piston has passed, in case it should not fall by its own weight. A copper 

 tube about 10 feet long, which is constantly kept hot by a small stove, also 

 fixed to the under side of the carriage, passes over the surface of the com- 

 position (which has been broken up by lifting the valve out of it), and ren- 



