Scientific Lectures. 191 



in the same building, a buttress-cap, of the same quarry weight, 

 which was roughed off to eighty tons before shipment, and, as now 

 finished, weighs sixty tons. The Great Eastern steamship was 

 launched sideways, being forced a thousand feet by very powerful 

 machinery. At this time she weighed upward of 10,000 tons. The 

 four tubes of the Britannia bridge each weighed 1,500 tons, and were 

 launched, transported a mile through a strong tideway, and then 

 elevated 100 feet perpendicularly. But we have only to refer to the 

 " house moving" of recent times, when a large brick building has 

 been moved a considerable distance ; or to more recent ones, when 

 whole blocks of large fine cut stone buildings in Chicago have been 

 elevated ten or fifteen feet, without disturbing the occupants in their 

 regular avocations ; and at the present time, w^hen all of the houses 

 on 130 acres of a compact part of Boston are being raised thirteen 

 feet ; and also at Sacramento, where the whole city is being raised 

 about fifteen feet. It may be interesting to compare the dimensions 

 and tonnage of some of the largest vessels of former times with 

 those of the present. The Ark was 450 feet long, seventy-five feet 

 wide, and forty-five feet high, and if its displacement corresponded 

 with the modern form of large vessels, its tonnage was from 12,000 

 to 15,000. " Show " ships were built by Hiero and the Ptolemies of 

 from 560 to 590 feet long, from sixty to seventy-six feet wide, and 

 eighty to 100 feet high. These vessels never went to sea, and could 

 only be maneuvered in calm water. They were manned by 4,000 

 rowers, 400 sailors, and 2,850 fighting men. Their tonnage was less 

 than that of the Ark, The Great Eastern is 695 feet long, eighty- 

 two feet beam, and fifty-six feet deep, and a tonnage of 22,500. Her 

 hull, engines, &c., weigh 12,000 tons, and she has a carrying capacity 

 of 8,000 tons of freight, and 4,000 passengers, or she could transport 

 10,000 troops with all their munitions. There are some modern men- 

 of-war of nearly 9,000 tons displacement. Tlie Cunard and American 

 sea steamers, those on the Sound and Hudson river, and even on the 

 Mississippi, range from 3,000 to 5,000 tons. The largest steam 

 engines in the world were those used for drainin": Harlem Mere. 

 The steam cylinders were twelve feet diameter and fifteen feet stroke, 

 and each one of the three engines drove eight water jDumps of sixty- 

 three and seventy-three inches diameter, and ten feet stroke. They 

 were employed for seven years in pumping the water out of the lake 

 to a depth of sixteen feet below the level of the sea, from an area of 

 56,000 acres, or twice that of Manhattan Island, which involved the 



