IT is much to be desired that the increasing interest concerning this great phenomenon should supply the only way of obviating the paucity and incompleteness of observations, by having a meeting of observers and advanced nature-students either at London or Bristol. The Utrecht observation says: “When this arch had obtained the length of 90° (which lasted only a few seconds), a separation was made in the middle of its length,” &c. I think this accounts for many of the discrepancies.