instruments," and consequently no steps were 

 taken to extend their use in Great Britain, 

 where several were then in operation. In Ca- 

 nadian waters, however, a better result seems 

 to have been obtained, as the Deputy Minister 

 of Marine and Fisheries, in his annual report 

 for 1872, summarizes the action of the whistles 

 in use there, from which it appears that they 

 have been heard at distances varying with their 

 diameter from 3 to 25 miles. 



The result of the experiments made by Prof. 

 Henry and Gen. Duane for the United States 

 Lighthouse Board, reported in 1874, goes to 

 show that the steam- whistle could be heard 

 far enough for practical uses in many posi- 

 tions. Prof. Henry found that he could hear 

 a 6-inch whistle 7i miles with a feeble op- 

 posing wind. Gen. Duane heard the 10-inch 

 whistle at Cape Elizabeth at his house in Port- 

 Ian 1 !, Maine, 9 miles distant, whenever it was 

 in operation. He heard it best during a heavy 

 northeast snow-storm, the wind blowing then 

 directly from him, and toward the source of the 

 sound. Gen. Duane also reported that " there 

 are six fog-signals on the coast of Maine ; these 



SOUND-SIGNALS. 



7-J.-J 



et, operated by a caloric engine, should only 

 be employed in exceptional cases, such as at 

 stations where no water can be procured, and 

 where from the proximity of otln 

 may be necessary to vary the nature of the 

 sound." Thus it would seem that the Dultoll 

 trumpet is an exceptionally fine instrument, 

 producing a sound of great penetration ami of 

 sufficient power for ordinary practical use, but 

 that to be kept going it requires skillful man- 

 agement and constant care. 



The Siren. The siren was adapted from the 

 instrument invented by Cagniard de la Tour, 

 by A. and F. Brown, of the New York City 

 Progress Works, under the guidance of Prof. 

 Henry, at the instance and for the use of the 

 United States Lighthouse Establishment, which 

 also adopted it for use as a fog-signal. The 

 siren of the first class consists of a huge trump- 

 et, somewhat of the size and shape used by 

 Daboll, with a wide mouth and a narrow throat, 

 and is sounded by driving compressed air or 

 steam through a disk placed in its throat. In 

 this disk are twelve radial slits ; back of the 

 fixed disk is a revolving plate containing as 



have frequently been heard at the distance of many similar openings. The plate is rotated 

 OA ;i -i,iMi /Hat ann a ii a .i a oa +>,o 2,400 times each minute, and each revolution 



20 miles," . . . which distance he gives as the 

 extreme limit of the 12-inch steam- whistle. 



Trumpets. -The Daboll trumpet was invented 

 by Mr. 0. L. Daboll, of Connecticut, who was 

 experimenting to meet the announced wants 

 of the United States Lighthouse Board. The 

 largest consists of a huge trumpet 17 feet long, 

 with a throat 3^- inches in diameter, and a flar- 

 ing mouth 38 inches across. In the trumpet 

 is a resounding cavity and a tongue-like steel 

 reed 10 inches long, 2| inches wide, 1 inch thick 

 at its fixed end, and half that at its free end. 

 Air is condensed in a reservoir and driven 

 through the trumpet by hot air or steam ma- 

 chinery at a pressure of from 15 to 20 pounds, 

 and is capable of making a shriek which can 

 be heard at a great distance for a certain num- 

 ber of seconds each minute, by about one quar- 

 ter of the power expended in the case of the 

 whistle. In all his experiments against and at 

 right angles and at other angles to the wind, 

 the trumpet stood first and the whistle came 

 next in power. In the trial of the relative 

 power of various instruments made by Gen. 

 Duane in 1874, the 12-inch whistle was re- 

 ported as exceeding the first-class Daboll trum- 

 pet. Beaseley reports that the trumpet has 

 done good work at various British stations, 

 .making itself heard from five to ten miles. 

 The engineer in charge of the lighthouses of 

 Canada says: "The expense for repairs, and 

 the frequent stoppages to make these repairs 

 during the four years they continued in use, 

 made them [the trumpets] expensive and un- 

 reliable. The frequent stoppages during foggy 

 weather made them sources of danger instead 

 of aids to navigation. The sound of these 

 trumpets has deteriorated during the last year 

 or so." Gen. Duane, reporting as to his ex- 

 periments in 1881, says: "The Daboll trump- 



causes the escape and interruption of twelve 

 ;'ets of air or steam through the openings in 

 the disk and rotating plate. In this way 28,800 

 vibrations are given during each minute that 

 the machine is operated ; and, as the vibrations 

 are taken up by the trumpet, an intense beam of 

 sound is projected from it. The siren is oper- 

 ated under a pressure of 72 pounds of steam, 

 and can be heard, under favorable circum- 

 stances, from twenty to thirty miles. "Its 

 density, quality, pitch, and penetration render 

 it dominant over such other noises after all 

 other signal-sounds have succumbed." It is 

 made of various sizes or classes, the number 

 of slits in its throat-disk diminishing with its 

 size. The dimensions given above are those 

 of the largest. (See engraving on page 448, 

 " Annual Cyclopaedia" for 1880.) 



The experiments made by Gen. Duane with 

 these three machines show that the siren can 

 be, all other things being equal, heard the 

 farthest, the steam-whistle stands next to the 

 siren, and the trumpet comes next to the whis- 

 tle. The machine which makes the most noise 

 consumes the most fuel. From the average of 

 the tests it appears that the power of the first- 

 class siren, the 12-inch whistle, and first-class 

 Daboll trumpet are thus expressed: siren 9, 

 whistle 7, trumpet 4; and their relative ex- 

 penditure of fuel thus: siren 9, whistle 3, trura- 



Sound-signals constitute so large a factor in 

 the safety of the navigator that the scientists 

 attached to the lighthouse establishments 

 the various countries have given much atten- 

 tion to their production and perfection, notably 

 Tyndall in England and Henry in this country. 

 The success of the United States has been such 

 that other countries have sent commissions here 



