464 



SCIENCE. 



[Vol. II., No. 35. 



cheaiD collecting-apparatus placed in both open 

 and confined waters to catch a ' set ' of spat, 

 which can then be transferred to ponds or open 

 beds. The methods of spawn-taking and pond- 

 culture introduced bj' the writer are inexpen- 

 sive and very simple, and can be understood 

 and conducted bj' anj' person of ordinarj- in- 

 telligence, and are fullj' described in papers 

 alread}' published, or in course of publication, 

 by the U. S. fish-commission, under the aiT- 

 spices of which he has been enabled to carry 

 out his investigations. The experimental dif- 

 ficulties have been overcome. It remains for 

 practical men to avail themselves of whatever 

 of value has been determined b}^ these experi- 

 ments. There are thousands of acres of salt- 

 marsh laud along the eastern coast of the 

 United States, which, with proper preparation, 

 might be made to yield a living to a large 

 number of persons, and which is now not pro- 

 ductive of any thing except mosquitoes and 

 malaria. 



Pond-culture has one other decided advan- 

 tage over culture in the open water ; namelj-, 

 that it is possible to effectually exclude from 

 the artificial enclosures certain enemies of the 

 oyster, such as whelks and star-fishes. 



J. A. Ryder. 



THE EXPLOSION OF THE RIVERDALE. 



The boiler of the steamer Riverdale exploded 

 on the 28th of August, a few minutes after the 

 boat had left her wharf at New York, and 

 started for her destination on the Hudson River 

 above the city. Several lives were lost, and 

 the boat itself was sunk in sixtj' feet of water. 

 The boiler was raised, and placed upon the 

 wharf near the Delamater iron-works ; and the 

 boat, a worthless wreck, was towed to the New- 

 Jersej' side of the river. 



The steamer had two- ' flue-boilers ' 25 feet 

 (7.6 m.) long, 6 feet 4 inches (1.93 m.) in 

 diameter, containing four ' direct ' flues 14 

 inches (0.36 m.) in diameter, two of 9 inches 

 (0.23 m.) diameter, and five 'return' flues 

 of 11-^ inches (0.28 m.) diameter. The shell 

 was of no. 3 iron, and the area of heating- 

 surface was 676 square feet (63 sq.m.). The 

 iron was of good quality, and was in good 

 condition throughout, except along the bot- 

 tom, where it gave way. The form, propor- 

 tions, and workmanship of the boiler were 

 good. The builders, Messrs. Fletcher & Har- 

 rison of New York, were among the most repu- 

 table constructors of engines and boilers in 

 that city, and were noted for doing good work. 



On examination, it was found that the bot- 



tom was corroded along its whole length, and 

 had been patched in a numlier of places where 

 the iron had become dangerously thin, and 

 that in some places the sheets were reduced 

 to one-fourth their original thickness. The 

 shell had been repcatedlj' patched, and five 

 ' soft patches ' were found on the girth-seams. 

 The rupture seems to have started in the thin 

 parts of the bottom, and to have followed the 

 weakened girth-seams quite around, and di- 

 vided the mass into two parts of nearly equal 

 size, tearing the middle sheet out of the shell 

 entirelj'. 



A coroner's jur^' made an inspection, exam- 

 ined such witnesses as could be found and 

 such experts as could be induced to testify', 

 and rendered a verdict to the efiect that the 

 boiler ruptured in consequence of the weakness 

 of the sheets on the bottom of the shell, which 

 were unable to sustain the working pressure 

 allowed by the U. S. inspector; which weak- 

 ness had been produced hy corrosion on the 

 interior, due to the action of the feed-water. 

 It was further asserted, that the boiler was 

 tested in June up to a pressure of 62 pounds 

 (5 atmos. abs.), and burst ten weeks later 

 under a pressure of but 32 pounds (3 atmos.), 

 in consequence of the neglect of the inspector 

 to observe its condition at the time of testing 

 it. The engine-driver and the inspector were 

 censured by a vote which was not unanimous. 

 The jury expressed the opinion that the pres- 

 ent law is not sufficiently explicit and manda- 

 torjr, and that the use of the test bj' hydrostatic 

 jDressure is insufficient to detect and reveal such 

 defects as here existed. 



The inspector acknowledged that he did not 

 try the strength of the boiler with the hammer, 

 as is now usual in all thorough examinations 

 by competent engineers, but merel}- looked it 

 over ; and that at previous inspections he had 

 not entered the boiler, but had onlj^ looked in 

 at the manhole. The evidence of the most 

 superficial and ineflicient ' inspection ' was con- 

 clusive ; and the fact that proper inspection 

 would have revealed the dangerous condition 

 of the boiler was equallj' well pro-\'en. The 

 so-called ' inspection ' was a farce ; and the 

 inspector, in a spirit of indifference or indo- 

 lence, took the chances of an explosion. 



The exploded boiler weighed 27,000 pounds 

 (12,247 kilos), and contained 25,000 pounds 

 (11,340 kilos) of water. The explosion was 

 not remarkablj' violent, but was what old engi- 

 neers are accustomed to call a ' burst ' rather 

 than an explosion. The consequences were, 

 however, sufficientl}^ serious. The energy 

 producing the effects seen in the case of a 



