The experiences of Eagle Clarke, Seebohm and others who have spent migration seasons at lighthouses might be quoted, but these two give a vivid description of what regularly takes place when weather conditions are unfavourable. Steady white lights are the most fatal to migrants, revolving lights, if white, are struck by some birds, but red lights seldom attract the passers. Mr Eagle Clarke thinks that birds are actually decoyed from their path and arrested in their course by the action of the lights; he says that a change from white to red lights at the Galloper Lightship stopped bird attraction. On the mainland a new high building or tower, new telegraph wires or other erections, until their presence is familiar, take toll of passage birds. Mr R. M. Barrington has for years collected information from the Irish lighthouses and light-vessels; some of his results were added to the work of the British Association Committee, and some he published himself (5). He emphasises the fact that these phenomena depend largely upon weather, and therefore are not trustworthy indications of the density at any time or place of migration. Out of 115 song thrushes killed at the lights and sent to him, 80 per cent struck during the fourth and first quarters of the moon, and the same rule holds good for other species. The intimate relation between the lunar phases and the number of examples killed was shown by statistics from 1888 to 1894. Out of 673 specimens received only 116 were killed when the moon was more than half full. Apart from fog or cloud, birds may fail to hit the land aimed at, either through accidental divergence from correct direction or wind drift. In November 1884 Mr Barrington received information of large numbers of rooks passing simultaneously at the Tearaght and Skelligs Lights--island stations 20 miles apart and each 9 miles off the Kerry coast. The birds arrived in continuous flocks from the westward--the open Atlantic--and passed in an easterly and landward direction; they came in small parties and in flocks numbering two or three hundred, on many days between the 2nd and 25th of the month. A few birds were noticed at the same time at stations on the south and east Irish coasts, and all alike making for the land. From similar observations made in other years he concludes that these were portions of hosts which had overshot the mark, and failing to find land had turned back. The weather charts, he adds, show no sufficient reason for the birds to have been blown out of their course by storms. The weather charts, as I have pointed out, do not indicate the force or direction of the wind at high altitudes; I suggest that these birds were carried rather than blown out of their way by strong currents at a higher altitude than recorded on the charts, and that having left the air currents they descended to the elevation of about 700 or 800 feet at which most of them were flying when they were observed making for the land.