January 5, 1894.] 



SCIENCE, 



S 



Weather Bureau. The balloon which the Secretary of 

 the Treasury had asked the Secretary of Agriculture to 

 permit the Weather Bureau to lend us, and which had 

 been shipped to us, did not arrive. Had it come we might 

 have had Professor Hazen looking down upon us from a 

 great height, and we should have had him at the end of a 

 rope, recording temperature, air currents, moisture, wind 

 and sound from 1,000 feet above, and at intervals of 

 25 feet, till we landed him on our deck or in the water. 

 Major Livermore, however, used toy balloons, with which 

 to ascertain the force and direction of the upper air cur- 

 rents. The paper balloons were, say, four feet high, and 

 one foot in diameter, at the widest j)art. They had an in- 

 genious attachment for producing hot air, which, at night, 

 lighted them, and made them for a while clearly visible. 

 The longest flight I saw one of these make was 15)^ min- 

 utes. Then the Major had spherical rubber balloons of, 

 say, nine inches through, which he filled with hydrogen 

 generated on the Myrtle, which were also quite useful. 



The fog-signals we were sent to observe were three 

 steam sirens and a steam whistle. Each signal has its 

 own peculiar characteristic. The second-class siren at 

 Little G-ull Island, for instance, gave, during a fog, a blast 

 of five seconds, and then after a silent interval of 40 sec- 

 onds, and another blast of five seconds, and it continued 

 this alternation of blast and interval while the fog contin- 

 ued. This blast and interval served to differentiq,te this 

 signal from other signals within ear- shot, and especially 

 that at New London light-house, which was a six seconds 

 blast, alternating with a silent interval of thirty seconds. 



The siren is the most powerful fog-signal in existence. 

 The English Government adopted it after a favorable re- 

 port on it made by a commission sent to this countrj' headed 

 by Sir Frederick Arrow, and also after a report by Pro- 

 fessor Tyndall, who then bore the same relation to the 

 English lighthouse establishment that Professor Henry 

 did to the United States lighthouse establishment, that is, 

 of scientific adviser. 



Tyndall says of the siren in his book on "Sound," third 

 edition, p. 316: "The steam siren is the most piowerful 

 fog-signal which has been tried in England." Again 

 Tyndall saj^s on p. 318: "We find the sound range on 

 clear calm days varying from 2 1/2 to 16 1/2 miles." 

 Again he saj's on page 319: "It may be relied ujoon at a 

 distance of two miles; in a great majority of cases it may 

 be relied upon at a distance of three miles, and in a major- 

 ity of cases at a distance greater than three miles." 



Now as to the full range of the instrument, Tyndall 

 says on page 321 of the same book: "The most conflict- 

 ing results were at first obtained. On the 19th of May, 

 1873, the sound range was 3 1/3 miles; on the 20th it was 

 5 1/2 miles; on the 2nd of June, 6 miles; on the 3ru, more 

 than 9 miles; on the 10th, 9 miles; on the 25th, 6 miles; 

 on the 26th, 9% miles; on the 1st of July, 123^' miles; on 

 the 2nd, i miles; while on the 3rd, with a clear, calm at- 

 mosphere and smooth sea, it was less than 3 miles." 



I have qiuoted this much from Tyndall, for while he ac- 

 cepts the siren, he damns it with faint praise, and what 

 he says is about the worst that has been said of it. The 

 French, who also adopted it, speak in much higher terms 

 of it, and the Light House Board, while constantly search- 

 ing, has found nothing better. It remains the best fog- 

 signal in the world, and it may be regarded as a constant 

 memorial of the work of Professor Henry, who, for light- 

 house purposes, was its inventor. 



But good as the siren is, it leaves much to be desired. 

 It is a great big clumsy, ugly machine, expensive to make,, 

 exjjensive to run, and expensive to keep in repair. It is 

 maintained to make a great big ugly noise continuously, 

 and of a certain kind and atcertain intervals. It makes the 

 noise, without regard to ethics or esthetics; but it might 



keep its pitch better; and it might maintain its intervals 

 better. It is not an instrument of j^recision. It has its 

 limitations. They are not entirely unconnected with the 

 pressure of its steam; in other words, with its manage- 

 ment. But it approximates exactness sufficiently near to 

 answer the purposes for which it is intended. When the 

 mariner hears it, and hears it aright, he knows where ho 

 is. The question we are discussing is not so' much con- 

 nected with the sound made as with the sound heard. It 

 is not the aberration of the sound, but the aberration of 

 the audition of the sound with which we are concerned. 



Now as to the method used to determine the intensity 

 of the sounds of the fog-signal we tested. This we did, 

 on this cruise, by ear, and on the same scale and in the 

 same way in which it was done in observations made in 

 1881 and 1885. 



Each of the party on the Clover used the scale of 10. 

 It was understood that 10 was the sound of the highest 

 intensity, and + the lowest sound observable. We divided 

 the scale, however, tlms: 1 1 plus, 1)4, 2 minus, and 

 then 2. Mr. Wallace, Major Livermore's assistant, used 

 the scale of 100. I have no doubt that is just as good as 

 my scale, but as I had commenced my observations on the 

 scale of 10, I carried that scale through these observations 

 in order that those made in '93 might be comparable Aith 

 those made in '85 and in '81. The question of i^ersonal 

 equation has arisen, but I have carefully avoided any 

 comparison of the mode of hearing, or rather accuracy of 

 hearing, between members of my party. My direction to 

 each was to record 10 as the highest sound of the fog- 

 signal that could be heard on board of the vessel in which 

 he was making observations. When they were as near 

 as thej' could get the vessel to the source of sound, the 

 distance was, as a rule, not more than one-fourth of a 

 mile. The minimum sound was 0. plus. One-half 

 of the sound between + and 10, I considered as 5, and 

 half-way between that and maximum was called T}^, and 

 half-way between 5 and 0+ was regarded as 2^2, and 

 then we divided still finer between those points. In that 

 way I think we got a practical solution of the Cjuestion,' 

 and are as nearly accurate as it is practicable for 

 observers to be, that is, for practical, but not for scientific, 

 ]Durposes. 



Each person preserves' his own scale throughout, re- 

 cording the maximum and minimum and medium, and 

 dividing between those points according to the accuracy 

 of his own ear. I noticed that difl'erent members of my 

 party, and of Major Livermore's party, did not mark in- 

 stances the same under some circumstances; but the dif- 

 ferences were slight, and they could be accounted for by 

 interfering noises in different parts of the ship, which 

 affected different hearers in those parts of the ship, so 

 that their hearing of the same noise was to a certain ex- 

 tent interfered with. I think the results reached were of 

 a jDractical character, although they were not such as 

 might be considered severely, or even scientifically, accu- 

 rate. They were not such as would have been recorded 

 by a self-registering machine, that is, they were not as 

 finely phrased. I tried to put myself in the place of the 

 mariner, who might hear a fog signal without knowing 

 what it was, and who might be forced to determine its 

 identity by the character of its blast, the intensity of its 

 blast, and the continuation of the silent interval between 

 blasts. 



Major Livermore has a large number of observations 

 which have been plotted, and I think will be comj^arable 

 with ours when ours are plotted. 



We are now having very delicate instruments made 

 with which to measure the character and the intensity of 

 the sounds made by fog-signals; and thus I hojie that 



