At Naarden, wednesday around 16.30 hours in North-Western direction, a strange aerial phenomenon was observed, it appears from a letter to the Hbl. A dark spot in the clouds moved in the fashion of an oilstain on water, that is being brought into motion.The spot divided itself in a number of smaller ones, which disappeared behind the horizon to come back again as a whole. The phenomenon was sometimes vague at other times more clearly visible. Something similar the observer had seen last year in the second half of January.