Page 835 . - miscellaneous 916 



LOBSTER POTS.— (See Fish traps and lobster pots.) 



LOCAL MAGNETIC ATTRACTION.— Information of this kind should originate in the Divi- 

 sion of Geomagnetism and Seismology. Local reports from the field should be forwarded to that 

 Division for verification and information. Include in the Coast Pilot the location, limits of area 

 involved, and maximum magnitude of error. 



LOCKS.— (See Canals.) 



LOG BOOMS. — Note where and when they may exist, if of interest to navigation. If the natural 

 width of the channel is restricted by them, or if some areas are enclosed by them to the extent of 

 affecting navigation, describe the condition. State if they are lighted. 



LOG RAFTS. — State if the navigation of a channel or canal is affected by these or if their presence 

 as tows may be a danger during fog or poor visibility. 



MAGNETIC COURSES AND BEARINGS.— Tables shall be included in the appendix to 

 facilitate the conversion of true directions in degrees to magnetic directions in points. These tables 

 should convert true directions for every 2° into magnetic directions to the nearest eighth point, and 

 should cover the range of variation in the region described in the Pilot. In most Pilots, the magnetic 

 directions in points can be given for every 2° of variation, but in some regions the range of variation is 

 too great for this. In such cases, the tables need not be made larger, but the directions in points may 

 be given for only every 4° or 5° of variation, as necessary. 



MAPS. — (See Blueprints and maps obtained locally.) 



MARINE RAILWAYS. — Give a description under each port where there is one or more. Give 

 maximum length, depth forward and aft, and tonnage of vessels that can be hauled out. Also give 

 the controlling depth in the channel to the plant. State if there is a machine shop, and, if so, give a 

 very general statement as to its capacity. Give the same information for floating drydocks and 

 graving docks. 



The table in the appendix shall give the dimensions, as above, of the largest vessel that can 

 be hauled out on a marine railway in every port, in the region covered. Similar information shall 

 be given in the same table for floating drydocks and for graving docks. State in each case if there 

 is a machine shop. More detailed information may be given in the text if desirable. (See Repair 

 Yards.) 



MARKER BUOYS.— Mention where used. 



MEAN LOW WATER, MEAN HIGH WATER, MEAN LOWER LOW WATER, ETC.— 

 (See Datums.) 



METERS. — Some navigators are more familiar with the metric system than with the English 

 system of measurement. For their convenience there shall be included in the appendix suitable tables 

 for the conversion of feet and fathoms to meters, and vice versa. 



METEOROLOGIC CONDITIONS.— Tables shall be included in the appendix giving the best 

 average information available for four or five different places. Obtain data from the Weather Bureau 

 and Coast Guard. 



MEASURED SPEED TRIAL COURSES. — To be referred to as such, unless the length is 

 exactly 1 mile. Give the exact length and course, and state whether the length is in nautical or statute 

 miles. Describe the appearance of marks, and give any other information of value to the user. Request 

 other vessels to keep well clear of the course while trials are being run. 



MOORING BUOYS.— (See Buoys.) 



MOUNTAINS. — Any hill more than 1,000 feet in elevation should be referred to as a mountain. 

 If snow-covered, state when, and give the elevation of the timber line. State whether the summit is 

 usually visible or cloud-capped. Give any details that may aid in its identification or that may make 

 it of unusual value. 



MUD ISLANDS. — Where these occur, as off the Mississippi Passes, describe them. 



NAMES. — ^(See Geographic names.) 



NUMBERING OF LINES. — In the part of the text where the detailed description of the region 

 is given, every fifth line should be numbered. Generally this will be from chapter 4 to the appendix. 

 This facilitates text references, particularly in the Supplements. (See 9137 and 915.) 



OBSTRUCTIONS.- — Where information is based on reports, or is of an indefinite character and 

 not determined by a survey, give dates, with all pertinent information. If it is from an unverified 

 report, state so. 



OBSTRUCTION LIGHTS.— These should be described if they are used, and as much detail as 

 necessary should be included. 



OYSTER CULTURE BEDS.— The general location of these should be given, with a proper 

 warning about speed and wash in the locality. 



