places of planets and comets, are generally computed for 12 o'clock midnight of Berlin or Greenwich or other places. But these are points that have themselves long since been discussed. I scarcely need to say anything further. I would not hesitate for a moment to give the preference to making the change of date take place at midnight, according to civil reckoning, in order to establish a uniformity with the customs of civil life. It, perhaps, may be important to remark that we could not introduce this change immediately, since the ephemerides are already computed and published for three or four years in advance. It would, therefore, be well to fix the epoch of change of normal dates to some distant time, such as 1890. I remain, very respectfully yours, W. VALENTINER. I may also mention that the practice that prevails among astronomers at the present time of reckoning the day from noon is by no means without exceptions. There are very important astronomical tables which reckon the day from midnight; for instance, in Delambre's Tables of the Sun; in Burg's, Burckhardt's and Damoiseau's Tables of the Moon; in Bouvard's Tables of Jupiter, Saturn, and Uranus, and in Damoiseau's Tables of Jupiter's Satellites, mean midnight is employed as the epoch of the tables. I may also mention that Laplace, in his Mecanique Celeste, adopts the mean midnight of Paris as the origin from which his day is reckoned. Hence there are great authorities, even among astronomers, in favor of commencing the day at midnight. General STRACHEY, Delegate of Great Britain. Sir, I observe that a very eminent American authority is present in this room, I mean Professor Hilgard. As he was invited to attend the meeting of this Conference, I suggest that the views of the Conference may be taken, whether he may not be invited to express his opinion on the point now under consideration. The PRESIDENT. With the concurrence of the Conference, the Chair will be most happy to ask Professor Hilgard to do us the favor to give us his opinion upon the question now before the Conference. No objection was made to the proposition of the President. Professor HILGARD arose and said. I thank you and the Conference very much for this invitation, and General STRACHEY for having proposed it to the Conference, but my opinion has been squarely expressed both in French and English in the report of a certain committee, that I am in favor of midnight at Greenwich as the beginning of the universal day, and of longitude being calculated both ways from Greenwich. I really cannot add anything to what has been said in the arguments already presented by Professor ADAMS, and I do not think that I ought to detain this Conference a moment by repeating the opinion he has expressed to all the experts in this matter.