The daily morning journal and courier., 1901-08-06
FOG SIGNAL EXPERIMENTS.
Important Researches By British EX-
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 Twenty-Five years ago the Trinlty House Corporation. with the advice and assistance of Professor Tyndall, carried out some interesting experi- ments at the South Foreland, near Do yer in regard to the use of sound for signalling to the mariner, to warn him of his proximity to danger at times when fog or other kinds of thick weather prevented his seeing the land or sea marks by day or the guiding or warning lights at night. The scien- tifc aspect of the question IS fuily given In the late editions Of Tyndall on Sound" and the practical results obtained have been shown in the large increase in the number of fog signal stations around our coasts and the adoption of certain instruments Tor producing sounds which had not pre- viously been employed in this country.
 With the lapse of time and the growth of the coast fog signal system, new knowledge has been gained and new developments have taken place, and it become necessary to test by practical and comparative experiments the value of certain theoretical inn movements which have from time to time been introduced, and to endeavor to determine some moot points which have arisen in connection with the gen eral question. Accordingly, a special committee of the Elder Brethren of Trinity House was appointed, the dep- utv master being chairman, with ,1air as scientific adviser, and the engineers of the three lighthouse boards, to con slider the present position of the sub feet and to carry out such experiments as they might regard as necessary. St. Catherine's Point, in the Isle of Wight was selected for the trials. Here there Is a lighthouse with a powerful electric arc light, produced by steam power which also serves for compressing air into receivers for sounding a perma- nent fog signal.
 At this station the committee has now been carrying on Its work during the last two or three weeks, observa- tiCns being made at sea each day by members of the committee on board the Trinity yacht Irene. One import ant question upon which the commit tee has been enga ged Is that of the relative merits of sirens as sound pro- ducing instruments, as compared with reeds. It does not seem probable that the vibrations set up by means of a reed can possibly be so powerful as those produced by means of siren, and it will be interesting to learn the results of the committees observations on this point,
 | The form of the trumpet or sound 1 projector is also receiving considerable attention, Lord Rayleigh himself hav- | ing certain theoretical views on the | point which he desires to have practi- | callv tested The relative merits of notes of different pitch, in regard to | their capability of penetrating the at mosphere under unfavorable condi- tions is another branch of the inquiry 1 which is being followed up by the com | mlttee, and some useful informa ton 1 on this point may result from the eX- | periments. The question of the most | effective and economical utilization of power for operating sound signals is | also receiving much consideration. It is obvious that there must be limta | tions in respect of the size of instru- l ments and the development of power for working them. Other matters for 1 inquiry and experimental test are questions connected with the best site l for a land sound signal, regard being | had to the nature of the coast line and the neighboring physical features also how a sea area which is to be guarded can be most efficiently covered by the so,,,d pf thn signal The yarious forms of siren and reed vibrators have come