Ray Bands. 391 
heavily charged with invisible vapor from the Gulf Stream sur- 
face. As these air masses arrive over the littoral and Narragan- 
sett waters, still cold with the accumulated cooling of the winter, 
their temperature rapidly sinks until the dew point is reached, 
and a fog results. It is in spring and early summer that 
this fog mechanism is perfect; but as the Bay, shore and shore 
waters get heated up in the advancing season, the change of 
temperature by shoreward transfer grows less, until in the late 
summer and fall, when fogs are rare 
4. Ray-bands.—The appearance familiarly known as “ the sun 
drawing water” is very frequent at Key West. It is not un- 
common to see the rays in the east, converging to the point oppo- 
site the sun, and as much below the horizon as the sun is above, 
which I will call the anti-sun. Sometimes the converging ray- 
bands in the east are nearly or quite as distinct as those in the 
west. The unusual frequency of these exhibitions is a result of 
the inshore drift of the Gulf Stream Cloud Bank. The ray- 
beams, through the breaks in the cloud masses, are made visible 
by the diffused and tenuous vapor incident to the evening 
cooling. ; 
and anti-sun, according to the customary perspective. Here is a 
notable point of singularity. So long as the W. and E. : 
truly rectilinear and sarees When a ray band is distin- 
| long 
_ 88 we see only the disjoined W. and HE. systems of convergent 
_ bands, we see them correctly in space according to simple per- 
Spective laws, just as when we look at the rails in a long, straight 
of railway. When however we look on a continuous 
luminous band across the sky, no distinctness of mental or logi- 
eal conviction can make that straight band or beam in atmo- 
Spheric space seem anything but a grand arch, widest near the 
_ own, and resting on the sun and anti-sun as piers. I think it 
