326 Ocean Magnetic Observations, 1905-16 



with a force 4, Beaufort scale. The ship's approxunate position was latitude 30?8 south, and longi- 

 tude 173° west. The nearest land was coral atolls, about 200 miles westward. 



b. A very heavy clap of thunder occurred on June 4 at 1 p. m. in approximate latitude 19?5 

 south and approximate longitude 169?9 west, about 20 miles southeast of rocky and timbered islands. 

 The wind of force 5 was from east-southeast. 



c. At 10 p. m. of the same day thunder and lightning were again noted in latitude 19?3 south and 

 in longitude 170?4 west, about 30 miles from the same islands. The wind was east, with force 4. 



7. An examination of the record also reveals the following facts, which appear to have an unpor- 

 tant bearing on the question referred to in first paragraph: 



a. There was no recorded occurrence of streak-lightning without the accompanying thunder. 



b. Displays of flash and sheet-hghtning, unaccompanied by thunder, were seen on one occasion 

 as high as 70°, but usually the recorded angular altitude was not above 35°. 



c. An unportant fact may be deduced from one of the recorded stomis, viz, the varying time- 

 interval between flash and clap, recorded in the lightning storm of October 10, clearly indicated the 

 approach and recession of the storm, and showed that the thunder was lost to the Carnegie's observers 

 when the storm was over 5 miles distant, as determined by the first and last intervals of about 20 

 seconds. 



d. Several times Ughtning, unaccompanied by thunder, was seen in calm weather, and only 

 once was it observed when the wind force exceeded 4 of the Beaufort scale. From these facts it 

 may be concluded that the noise on ship is not the reason for the apparent silence of some lightning- 

 storms at sea. 



e. The record shows, however, that thunder was heard at no greater distance than 600 nautical 

 miles from land, which in this extreme case was of such mountainous character as would tend to 

 intensify the thunder. 



It may be concluded from 7a, lb, Ic, and Id that many hghtning storms are too distant to be 

 heard, while from 7e it can only be said that, if the presence of land is necessary to make audible the 

 sound of thunder at sea, as has been suggested, then it is possible that the land may be very distant 

 at times, so far even as 600 miles. 



The facts thus far noted are yet too few to warrant any final conclusions. It is expected that 

 additional data will be available before the present cruise of the Carnegie will have ended. 



J. P. Ault: On the Sub- Antarctic Voyage of the Carnegie from Ltttelton to Lyttelton, 

 VIA South Georgia, December 6, 1915, to April 1, 1916. 



I beg to submit the following report on the circumnavigation trip of the Carnegie from Lyttelton 

 to Lyttelton via South Georgia, December 6, 1915, to April 1, 1916. 



For the first week after leaving Lyttelton the winds were mainly from the SSW, forcing us con- 

 siderably to the eastward of our route; so much so that we sighted the Antipodes, bearing south, 

 distant 20 miles, on December 9, and would have passed over the charted position of the Nimrod 

 Group had the wind remained in the south another 12 hours. It had not been the intention to go 

 near this group, but the adverse winds sending us so near them, it was decided to stand on toward the 

 east another day, to endeavor to sight them; but the wind shifted to the north 12 hours too soon and 

 we passed 40 miles to the SW of the position. [The Nimrod Islands were stated to have been seen, 

 at a considerable distance, by Capt. Henry Eilbech in the Nimrod in 1828, who placed them in about 

 56?5 S and 158?5 W.'] 



On December 7, a mirage presenting the appearance of distinct and extensive land was seen in 

 the west, in the direction of Banks Peninsula, which was 190 miles distant at the time. 



We crossed the 180th meridian December 9, so repeated the date as December 9 (2). Our first 

 piece of ice was sighted on December 18, lat. 60° 12' S, long. 150° 46' W, and on December 19, 30 

 icebergs, some being over 400 feet high and 1 mile long, were passed. We had snow on December 18, 

 19, 20, and 21, and rather wintry weather. The barometer dropped to 28.26 inches on December 18, 

 during the snow storm. No icebergs were seen after December 24 until January 10, just before 

 arrival at South Georgia, when 8 or 10 good-sized bergs were passed. 



As our route lay near the charted position of Dougherty Island, we determined to look for it. 

 On the afternoon of December 24, the cry of "land ahead" was given and we saw what appeared to 



'See footnote, page 327. 



