368 



NATURE 



{August I, 1878 



The bridge was severely tested by Gen. Hutchinson, 

 the Government Inspector of Railways, in February of 

 this year. Five locomotive engines of 72 tons weight 

 each were placed on the large spans and run over them 

 at considerable speed. This weight of 360 tons for each 

 of the 245' spans will never be reached in the working of 

 the railway, 162 tons being the greatest load resulting on 

 each span from the heaviest goods train. Under the 

 test load the deflection of any of the spans did not exceed 

 the calculated limit, and the lateral movement during the 

 passage of trains was but trifling. 



On June i the bridge was opened for ordinary traffic, 

 and it is now daily crossed by numerous and heavy trains. 

 For the North British Railway Company and the travelling 

 public its completion is of very great importance. But 

 the work must have a still greater importance in the eyes 

 of engineers and those interested in the practical applica- 

 tion of scientific principles, as many neAv methods to 

 overcome formidable difficulties were successfully carried 

 out, some of Avhich might with advantage be used in 

 similar structures. A. Grothe 



THE NORWEGIAN NORTH ATLANTIC 

 EXPEDITION 



THE expedition left Bergen on June 15, and pro- 

 ceeded without interruption to the Westfjord, in 

 Nordland, where we had our first station. A tempera- 

 ture-series was here taken with Negretti and Zambra's 

 new deep-sea thermometer, which showed \cP"j C. on the 

 surface, a minimum of 4°'4 in a depth of 40 fathoms, 

 and 6°*5 at the bottom in 340 fathoms. The Voringen 

 stopped some hours at Tromso to take on board a pilot, 

 and proceeded to the Altenfjord, where we found 7°'3 at 

 the surface, a minimum of 2° 7 in a depth of 100 fathoms, 

 and 3°'9 in 220 fathoms at bottom. From Alten we went 

 to Hammerfest, where we stayed two days. Our next 

 stations were in the Porsangerfjord and in the Tanafjord. 

 On all these stations we dredged and trawled with good 

 success. On June 26 we were lying at Wardo, where 

 Capt. Wille made magnetical observations of force and 

 inclination. The declination was determined the day 

 before off the coast by going round with the ship, and 

 taking bearings of the sun on different courses. On 

 June 27 we put to sea on an eastward course. The 

 barometer was falling rapidly, and at midnight the wind 

 and sea got so heavy, that the ship was put with the stem 

 against the wind, and we were lying almost still. This 

 situation lasted till the next night, when we again pro- 

 ceeded on our course, but very slowly, the ship pitching 

 heavily, and the wind being constantly ahead. In this 

 manner we found 0° C. at the sea bottom, in about 7 1° 30' N. 

 and 36° 30' E. from Greenwich. We then sailed northwards 

 and westwards, and passed the said bottom temperature 

 several times, so that I am now able to give its situation 

 pretty accurately in the chart. The northern part of this 

 zero line forms a bay east of Bear (Cherry) Island, where 

 the warmer water reaches 'a higher latitude, and runs close 

 to the east side of that island, where we for the first time 

 observed the polar ice. The temperature-series showed 

 the accuracy of Weyprecht's observations, that the 

 colder Polar water edges itself along the bottom from the 

 east and north, and the warm Atlantic water runs out in 

 a similar edge in the contrary direction towards Novaya 

 Zemlya and Franz-Joseph Land. On July 4 we were at 

 Bear Island, on the south-east side. We were happy to 

 find the sky almost perfectly clear, a rather rare occur- 

 rence on this island. The ship was anchored outside the 

 open coast, and we went on shore at the mouth of a little 

 river, in the vicinity of which there stands a hut, which 

 has been the abode of wintering parties. Here we de- 

 posited the mail which we brought for the Dutch polar 

 expedition in the Wilhcm Bafentz schooner. The place 



was marked with a flag, and the letters, &c., dug down, 

 inclosed in an outer wooden and an inner sheet-iron 

 soldered box, I took a tour upon the nearest hills, col- 

 lected some rock specimens, and measured the altitude 

 of the highest peak on Bear Island, Mount Misery. The 

 calculation gave me a height of 1,787 English feet, a 

 result which I regard as very accurate. After dinner we 

 weighed and proceeded to the south-west ; crossed, the 

 following day, the zero line of bottom temperature on 

 the bank between Bear Island and Norway, sounded in 

 1,024 fathoms on July 6 in lat. 73° 6' N., long. u° 56' 

 E. ; we went then east- south-eastwards, crossed again 

 the zero temperature hne, and shaped our course for 

 Hammerfest, where we arrived on the 8th. The ship is 

 now cleaned ; we take in coal, and expect to be ready to 

 sail on a westward cruise in three days. Our first cruise 

 has yielded thirty-eight soundings, seventeen temperature 

 series, ten dredgings, and seven trawlings, all successful. 

 New species of animals have been found by our zoologists. 

 Negretti and Zambra's newest reversible deep-sea ther- 

 mometer has done us great service ; the instrument has, 

 almost Avithout exception, worked very well. I have 

 constantly compared its readings from the bottom with 

 the reading of the Casella, Buchanan's improved form, 

 and found a very close agreement. As I supposed, the 

 wooden box which carries the thermometer gets water- 

 soaked after a few experiments in a few hundred fathoms, 

 so that it no longer floats, but this is no drawback, as 

 the lead rushes down so fast that the thermometer 

 always keeps its upright situation till it reaches the 

 bottom, and it never requires more than three minutes 

 for a perfect accommodiation to o'l of a degree. I there- 

 fore regard this instrument as a very important improve- 

 ment, and feel much obliged to the inventors and makers. 

 Hammerfest, July 10 H. MOHN 



THE TASIMETER 



MR. EDISON has applied the principle of his carbon 

 telephone to a new instrument which is said to be 

 a measurer of infinitesimal pressure. The principle is 

 the variation of the electric resistance of a carbon button 

 due to variation of pressure, and the instrument is said 

 to be an extremely delicate thermoscope. We have not 

 yet, however, received any authentic account of its per- 

 formance or of its accuracy, but its ingenuity certainly 

 deserves a description, for which we are indebted to the 

 Scientific American. 



It is the outcome of Mr. Edison's carbon telephone- 

 Having experimented with diaphragms of various thick- 

 nesses, he ascertained that the best results were secured 

 by using the thicker diaphragms. At this stage, however, 

 he experienced a new difficulty. So sensitive was the 

 carbon button to changes of condition, that the expansion 

 of the rubber telephone handle rendered the instrument 

 inarticulate, and finally inoperative. Iron handles were 

 substituted with a similar result, but with the additional 

 feature of musical- and creaky tones distinctly audible 

 in the receiving instrument. These sounds Mr. Edison 

 attributed to the movement of the molecules of iron 

 among themselves during expansion. He calls them 

 "molecular music." To avoid these disturbances in the 

 telephone, the handle was dispensed with ; but it had 

 done a great service in revealing the extreme sensitive- 

 ness of the carbon button, and this discovery opened 

 the way for the invention of the new and wonderful 

 instrument. 



The micro-tasimeter is represented in perspective m 

 Figs. I and 2, in section in Fig. 3, and the plan upon 

 which it is arranged in the electric circuit is shown m 

 Fig. 4. . . c 



The instrument consistsessentially of arigid iron frame 

 for holding the carbon button, which is placed between 



