December 1, 1891.] 



KNO\A/^LEDGE 



235 



film was effected by a red-hot rivet or a piece of burning 

 waste thrown overboard from some ship contiguous to the 

 WUdilinrer. Experiments made with some oil taken from 

 the tanks showed a specific gravity of -T-ISS, and a power 

 per gallon of rendering inflammable 133 cubic feet of air. 

 When the oil was poured upon water the resulting film 

 was easily ignited by a flame or any brightly red-hot solid. 

 The evaporation of its volatile properties was so rapid that 

 in ten minutes a lighted match failed to ignite the oil, 

 while with twenty minutes' exposure it was necessary to 

 blow a flame upon it to set it on fire, and after half-an- 

 hour it was very difficult to light the oil by any means 

 whatever. The teaching of the Wihlfioirer disaster is too 

 important to be ignored. It is dreadful to contemplate 

 what accidents may occur through the presence of Petro- 

 leum upon the surface of the waters of crowded harbours. 

 At Batoum the water is usually covered with oil to the 

 distance of three-quarters of a mile from the shore, while 

 practically the same condition of things obtains at 

 Philadelphia. 



The teachings of Petroleum disasters are, however, by 

 no means limited to the above two cases. The latest 

 horror occurred on board the steamer Tmicnmlle, when in 

 the dry dock at Newport, on the 11th May last. Like the 

 Wildfldicer, the TawdrviJlc was built in 1889, and 

 specially constructed for the carriage of Petroleum in bulk. 

 The oil tanks were six compartments, extending from the 

 skin of the ship up to the lower deck, and were sub-dinded 

 again by a longitudinal bulkhead. Each tank was fitted 

 with an expansion space, and these again were provided 

 with man-holes. The vessel was equipped with the electric 

 light on the double wire system. The cables were enclosed 

 in a wooden frame and thorovighly insulated from each 

 other. Switches were provided for the purpose of effecting 

 communication between the main and portable cables. 

 The connection was made by a ball and socket lever and 

 covered with a brass cap. There were six portable cables, 

 and the portable lamps were protected by clear glass globes 

 of considerable thickness over the incandescent globes, the 

 glass globes again being protected by four brass bars. The 

 vessel was employed in carrying crude Petroleum from 

 Philadelphia to Havre. She discharged her last cargo 

 there and sailed for Newport on April 18th, which port she 

 reached two days later, and was placed in dry dock on the 

 same date. She went into dock a " dirty ship," i.e., one 

 which was not properly cleansed. A considerable quantity 

 of oil was known to be in the ballast tank, which was a space 

 of about 6000 cubic feet. Some of the oil remaining in the 

 vessel was discharged into the dock and a red-hot rivet 

 falling upon it set it on fire, doing considerable damage to 

 the vessel. This was on the 23rd April. The vessel re- 

 mained under repairs until May 11th, when an explosion 

 occurred which wrecked the vessel and resulted in the 

 loss of six lives. Several portable forges were being 

 used on board the vessel, as much rivetting of her tanks 

 was necessary. The residual oil in the ballast tank 

 was removed so far as possible by drilling a hole in the 

 bottom of the vessel and allowing the oil to run through 

 into the dock. It was in this ballast tank that the 

 explosion occurred with the violence stated above. The 

 immediate cause of the disaster it is impossible to 

 ascertain, but where portable forges and rivetting are 

 carried on in spaces adjacent to those in which Petroleum 

 vapour must have accumulated, a catastrophe is simply 

 invited. Tlie flames, according to some witnesses, reached 

 as high as the top of tlie fore-mast, and the wrecking of 

 the vessel is proof of the powerfully explosive character of 

 Petroleum vapour. Assiuuing tluit one gallon of the oil 

 would render 200 cubic feet of air feebly, and sixty cubic feet 



of air strongly, explosive, it will be seen that the presence 

 of very little oil would suffice to fill the empty space of the 

 ballast tank with a highly explosive compound. 



What alterations in the pumping and ventilating 

 appliances these disasters will lead to will be watched 

 with the greatest interest. The better cleansing of oil 

 steamers should be insisted upon. Spaces iuto which oil 

 may leak are perhaps greater sources of danger than the 

 tanks themselves, and adequate provision should be made 

 for their effective cleansing in a thoroughly scientific 

 manner. But the machinery of Petroleum conveyance 

 needs revising and bringing up to date. The powers of 

 harbour authorities are very limited, and they could not 

 make bye-laws that would much diminish the risk unless 

 the owners, and those who have to see to the details of 

 the traffic, become alive to the dangers. They, by the 

 loss of their lives and property, have already the highest 

 incentive to adopt precautions. Refined Petroleum that 

 has a higher flashmg point than 73' Fahr. (Abel test), i.e., 

 " mineral oil," as distinguished from " mineral spirit," is 

 outside the pale of the law. The dangers fi-om oils whose 

 vapours ignite at low temperatures are obvious. An 

 eminent firm of oil manufacturers say that they have 

 found some oils offered for liibricati'i;/ jiurpases which gave 

 oS' dum/erom gases at a temperature of between 70^ and 

 80^ Fahr. 



The Petroleum trade has developed enormously, and is 

 still doing so. It can hardly be said, however, that the 

 conduct of the trade is prosecuted according to the present 

 teachings of science. The development of the trade has 

 been attended with a much greater amount of disaster 

 than even the dangerous nature of Petroleum wan-ants, 

 and it is to be hoped the object-lessons of the accidents 

 discussed will appeal to all those responsible for a diminu- 

 tion of them. One feature of the trade cannot be too 

 strongly deprecated. The carriage of Petroleum in bulk 

 requires vessels of a vastly different tj'pe to the average 

 merchant vessel. Yet the British shipmaster, if he 

 possesses the regulation Board of Trade master's certifi- 

 cate, is considered competent to command a tank steamer, 

 with all its special mechanical apparatus for tank dis- 

 charge, &c., and electrical equipment. Special conditions 

 require special training, and, at the very least, there 

 should be on every oil steamer a skilled electrician com- 

 petent to effect repairs and to see that the electrical 

 lighting is carried out on scientific lines. 



SEA-URCHINS. 



By R. Lydekker, B.A.Cantab. 



PROBABLY most visitors to the seaside are more or 

 less familiar with the shells of those marine 

 creatures commonly known as Sea- Urchins, or 

 Sea-Eggs, this acquaintance being usually due 

 either to finding them cast up on sandy beaches, 

 or to seeing them offered for sale by the vendors of 

 curiosities and natural history objects. In many in- 

 stances it is probable that the acquaintance ends here, 

 although in others these objects may have been submitted 

 to a fuller examination ; but, in any case, we venture to 

 say it is comparatively few who have studied them with 

 the care and attention that their beauty of form and pecu- 

 liar structure demands, and still fewer who know anything 

 about their history in past times. Those, however, who 

 care to take up the subject will find it one of more than 

 usual interest, and we accordingly propose in this article 

 to place before the reader some of the leading features and 



