BYSSUS 



developed from the discovery that electrodes 

 thrust in ocean mud could pick up electrical 

 energy from microorganisms under the bottom 

 slime. 

 built platform — A bank of sediment which flanks 

 the marine-cut terrace or wave cut platform on 

 its seaward margin. Tlie sediment is derived 

 from marine erosion and from rivers. (2) 

 bulk modulus — See coefficient of compressibil- 

 ity, 

 bull kelp — 1. One of a genus {N ereocystis) of 

 large brown algae, which consist of a massive 

 holdfast, a long tough stipe terminated by an 

 elongate bulbous pneumatocyst, from which 

 four lamina-bearing branches radiate. This 

 genus occurs only on the Pacific coast of North 

 America from southern California northward 

 into Alaska and may reach lengths of 100 feet or 

 more. 



2. One of a genus {Durvillea) of large brown 

 algae with broad, massive, leathery laminae, 

 which grows on rocks in the intertidal zone in 

 the cold waters of South America and New Zea- 

 land. 

 bummock — From the point of view of the sub- 

 mariner, a downward projection from the un- 

 derside of the ice canopy ; the submerged coun- 

 terpart of a hummock. (7) 

 buoy — A float; especially a floating object moored 

 to the bottom, to mark a channel, anchor, shoal 

 rock, etc. Some common types are : 

 A nun or nut buoy is conical in shape ; 

 A can buoy is squat, and cylindrical or nearly 

 cylindrical above water and conical below 

 water ; 

 A spar buoy is a vertical, slender spar an- 

 chored at one end ; 

 A bell buoy is one having a bell operated 



mechanically or by the action of waves, 



usually marking shoals or rocks ; 

 A whistling buoy is similarly operated (by 



wave action), marking shoals or channel 



entrances ; 

 A dan buoy carries a pole with a flag or light 



on it. 

 (61) 

 buoyancy — 1. That property of an object that en- 

 ables it to float on the surface of a liquid, or 

 ascend through and remain freely suspended in 

 a compressible fluid such as the atmosphere. 

 Quantitatively, it may be expressed as the ratio 

 of the specific weight of the fluid to the specific 

 weight of the object; or, in another mannei-, by 

 the weight of the fluid displaced minus the 

 weight of the object. 



2. (or buoyant force; also called Archime- 

 dean iuoycmt force). The upward force ex- 

 erted upon a parcel of fluid (or an object within 

 the fluid) in a gravitational field by virtue of 

 the density difference between the parcel (or ob- 

 ject) and that of the surrounding fluid. 



(5) 



buoyant force — See buoyancy (sense 2) . 



burning of the sea — See sea fire. 



Buys Ballot's law — A law describing the rela- 

 tionship of the horizontal wind direction in the 

 atmosphere to the pressure distribution ; if one 

 stands with his back to the wind, the pressure to 

 the left is lower than to the right in the Northern 

 Hemisphere. In the Southern Hemisphere, the 

 relation is reversed. 



This law was formulated in 1857 by the Dutch 

 meteorologist Buys Ballot and is a qualitative 

 statement of the geostrophic wind equation. 

 (5) 



byssal thread — A part of a byssus. 



byssus — A hairy attachment structure secreted by 

 certain pelecypods. 



207-109 o — 66 



27 



