70 ANNUAL OF SCIENTIFIC DISCOVERY. 



LEE-WAT INDICATOR. 



THIS contrivance, the invention of Mr. Wilder, of Detroit, is an- 

 other of the instruments intended to show the lee-way or side-way 

 drifting from her course which every ship makes, to a greater or less 

 degree. All these inventions have hitherto been unsuccessful, but 

 this seems to approach nearer to what is required. A tube about 4 

 inches in diameter passes down through the binnacle to the keel of 

 the vessel, through which passes a rod, and to this a vane is attached, 

 about 8 inches "deep and 2 feet long. As this is in dense water, it 

 will be operated on by any drifting of the vessel, which will be indi- 

 cated by a needle at the top of the rod, which is placed upon a plate 

 on which the degrees are marked. This plate can be most conve- 

 niently placed between the two compasses in the binnacle, and therefore 

 directly in front of the helmsman. Should this invention answer the 

 purpose intended, the latitude and longitude of a ship can be ascer- 

 tained very nearly, without an observation of the sun, merely by cal- 

 culating the " dead reckoning," or distance run by the log. Any- 

 thing, however, projecting from the keel as this does, is very much 

 exposed to be knocked off by whatever conies in contact with it. 

 Detrpit Bulletin. 



MACHINE TO INDICATE A VESSEL'S VARIATION FROM HER COURSE. 



IF we understand correctly the description of this contrivance, the 

 slightest variation from the true course of the ship is marked so that 

 the officer in command can at once detect any careless steering. It is 

 the invention of Mr. A. E. Dayton, of St. Lawrence Co., N. Y., 

 and is simply a new combination of the chemical telegraph. A small 

 fillet of the chemical paper is combined with the compass, and it is 

 drawn forward slowly by clock work. The fillet is marked with par- 

 allel lines, and a small steel point in connection with the wire of the 

 battery rests on it. This will make a straight line always if the ves- 

 sel does not diverge from her track, but every divergence of the ves- 

 sel from her direct route will be indicated by the point marking either 

 angular or curved lines on the fillet. 



AIR-WHISTLE. 



MR. C. DABOLL, of New London, Conn., has invented a whistle that 

 speaks w T ith a most " miraculous organ" whenever its services are 

 required for the purpose of alarm or warning. It is designed for the 

 use of vessels at sea or on the coast, as on our eastern shores, where 

 dense fogs prevail, and vessels are liable to come in collision before 

 they are conscious of each other's approach. Its great advantage is 

 its power of communicating sounds for a distance of from 4 to 5 

 miles, far exceeding the largest bells. An experimental one has been 

 placed on Barllett's Reef, and the pilot of the Lawrence states that 

 he has heard it when about 4 miles off from Bartlett's Reef, against 

 the wind, which was blowing quite fresh at the time. This was on a 

 clear day, and when the whistle was blown, at his request, and also 



