Page:The evolution of worlds - Lowell.djvu/136

106 Requested to look for them, the observatory at Flagstaff was not long in corroborating this interesting phenomenon. The peculiarity about them pointed out by Mr. Bolton is that they traverse the belt at an angle of about 45° to the vertical, proceeding from caret-shaped dark spots projecting into the bright belt from the dark ones on either side. They exist all round the equator and are found indifferently dextrous or sinister—sometimes vertical. For there are others that go straight across. Nor are they confined to the bright equatorial belt, but are to be seen traversing all of the bright belts both north or south up to the polar hoods. From its sombreness it seems that we are here regarding a phenomenon in the negative; remarking it by what it has left behind, not by what it has accomplished. For the wisps are not wisps of cloud, since they are dark, not light, but gaps strung out in the clouds themselves.

Recently photographs of Jupiter have been secured at Flagstaff, by the new methods there of planetary photography, showing a surprising amount of detail. The wisps come out with certainty, and the white spots, which are such a curious feature of the disk, have also left their impress on the plate. Not the least of the services thus rendered by the camera is the accurate positioning of the belts made possible by it. Micrometric measures are all very well when nothing better