i86 THE POPULAR SCIENCE MONTHLY. 



weather that can occur in an hour, may be succinctly and accurately 

 described : 



b. — Clear blue sky. 



c. — Cloudy weather. 



(7. — Drizzling or light rain. 



f. — Fog, or foggy weather. 



g. — Gloomy, or dark, stormy-looking weather. 



A.— Hail. 



/. — Lightning. 



m. — Misty weather. 



o. — Overcast. 



2). — Passing showers of rain. 



q. — Squally weather. 



7\ — Rainy weather, or continuous rain. 



s. — Snow, snowy weather, or snow falling. 



^.— Thunder. 



i(. — Ugly appearances, or threatening weather. 



V. — Variable weather. 



vj. — Wet, or heavy dew. 



z. — Hazy. 



We now arrive at the method of compilation, and for this several 

 blank forms are used which will be described as the necessity arises to 

 speak of each kind. 



First, however, eveiy log-book and journal is closely examined for 

 any errors it may contain, and, if such exist, they are scored with a 

 red pencil, and hence do not enter into the compilation or charts. 



Whatever judgment of the log-book this scrutiny warrants, is en- 

 tered in it for guidance of the compiler. 



The first blank to be used is Form A — a sheet 36 inches by 20. 

 It is a projection according to Mercator of that pai't of the sphere 

 between the 70th parallels of latitude north and south. Beginning 

 with the equator and the meridian of Greenwich, parallels and meridi- 

 ans are drawn at every fifth degree, thus dividing the ocean, like a 

 chess-board, into small squares. These are numbered consecutively 

 from 1 to 1,G67, so that, either by its number or its limits in latitude 

 and longitude, the expanse of ocean covered by any square can be 

 designated. 



When a ship makes a passage under sail, she will cross certain of 

 these squares on devious courses, and be in each square a short or a 

 long period according as the winds and weather favor or oppose her. 

 The particular square in each day can be ascertained by referring the 

 noon position to Form A ; and the hour of entering and of leaving it 

 can be found by working the ship's run, by means of the courses 

 and distances, backward or forward as necessary, from the noon posi- 

 tion. Then, drawing heavy lines across the left-hand or meteoro- 

 logical page of the log-book at the hours of entry and of exit, it 



