April 30, 1886.] 



SCIENCE. 



389 



tions in regard to it. The hydrographic office will 

 have it further examined at the first opportunity. 



From this point the easterly course was con- 

 tinued until the line of soundings taken three 

 years before by the Enterprise was crossed, in 

 about latitude 27° south, longitude 27° west ; and 

 then the line ran almost directly for the Island of 

 Fernando de Noronha, the depths averaging about 

 2,800 fathoms, until the vicinity of tins island was 

 shown by a sounding of 2,280 fathoms. Beyond, 

 the depths increased to an average of about 2,500 

 fathoms until the neighborhood of Barbadoes was 

 reached, when the water shoaled again to 1,204 

 fathoms. 



The depth of 2,560 fathoms in longitude 55° 

 west, latitude 12° north, is within thirty miles of 

 a sounding of 2,570 fathoms taken by the U.S. brig 

 Dolphin in 1852 ; that of 2,714 fathoms in latitude 

 11° 25' north, longitude 52° 50' west, is within thirty 

 miles of a sounding of 2,780 fathoms, also taken 

 by the Dolphin in 1852. 



After leaving St. Thomas, sounding was again 

 resumed ; the first cast, taken in latitude 19° 53' 

 north, longitude 65° 45' west, showing 4,529 fath- 

 oms. As this point is about forty miles east-north- 

 east of the famous cast of 4,561 fathoms, made by 

 Lieutenant-Commander Brownson, U.S.N. , with 

 the coast and geodetic survey steamer Blake, the 

 great depth obtained is peculiarly interesting. 

 Beyond this deep the line ran towards Cape 

 Hatteras, over a section formerly unsounded, show- 

 ing an average depth of about 3,000 fathoms. 



Commander Barker further says, "A ship like 

 the Enterprise can undoubtedly sound hi any sea 

 and in any weather in winch she can steam ahead 

 fast enough to stem the wind and steer. The 

 brake used was a plain piece of rope made fast in- 

 board of, and abreast of, the lower part of the 

 reel, then around the groove outboard, and held 

 in the hand above. This brake controls the reel 

 perfectly, it being possible to hold the shot, 

 without any effort, at a great depth. In rolling 

 heavily it is very easy to keep a constant strain on 

 the wire. A distance-line of at least 12 fathoms 

 was used, with a piece of lead weighing about a 

 pound near the grommet. One length of the 

 large American wire was put on next to the dis- 

 tance-line, as it was not so likely to kink. To 

 prevent the shot from catching on top of the cup, a 

 tripping-line was used, consisting of a piece of small 

 stuff, one end made fast to the rod just below and in 

 the plane of the hook, and the other end around 

 the top of the cup : this line is of such a length as 

 to be taut when the cup is closed. In nearly all 

 the casts, sail was made after reeling in to 2,000 

 fathoms, but only such as not to give a greater 

 speed than four knots. When reeled in to 1,000 



fathoms, all sail was made. The wind was always 

 kept on the starboard side, so as to have the wire 

 to windward. The only accident which happened 

 on the trip was due to the wire catching some part 

 of the ship, probably the propeller : it was dark at 

 the time, and she was going at the rate of about 

 seven knots. " The accompanying chart shows the 

 principal lines of deep-sea soundings south of lati- 

 tude 40° north. The hydrographic office has in 

 course of preparation a series of charts showing 

 the contours of the ocean-beds as determined by 

 all reliable soundings that have been taken. 



J. R. Bartlett. 



U. S. hydrographic office. 



LONDON LETTER. 



After more than seven years of investigation 

 and experiment, the Royal commission appointed 

 to inquire into accidents in mines has presented 

 its final report, which was issued on Saturday in 

 the form of one hundred and ten pages of a large 

 blue-book. The delay is accounted for by the 

 long and difficult quest on which the commission- 

 ers were sent. They were to report, not only on 

 the causes of mining accidents, but also on "the 

 possible means of preventing their recurrence, or 

 limiting then* disastrous consequences." Not much 

 is recommended in the way of mere legislative 

 changes, but the scientific recommendations are 

 most interesting and important. For example : 

 with reference to the difficult question of the best 

 method of firing shots in mines, they state that 

 ' ' electrical exploding appliances present very im- 

 portant advantages from the point of view of 

 safety, over any kind of fuze which has to be 

 ignited by the application of flame to its exposed 

 extremity, as the firing of shots by then means 

 is not only accomplished out of contact with air, 

 but is also under most complete control up to the 

 moment of firing. Their simplicity and certainty 

 of action has been much increased of late years, 

 while their cost has been greatly reduced, and 

 but little instruction is now needed to insure their 

 efficient employment by persons of average intel- 

 ligence. The use of electrical arrangements for 

 firing shots in mines where the employment of 

 powder for blasting is inadmissible should be en- 

 couraged as much as possible." 



Again, they state that " it has been shown that 

 mines which have hitherto been considered free 

 from fire-damp may have the air which passes 

 through them vitiated to an extent corresponding 

 to about two per cent of its volume of marsh-gas. 

 The air in many such mines may probably never 

 be entirely free from explosive gas ; at all events, 

 in the neighborhood of freshly cut faces of coal 



