246 
NATURE 
or cS ae over ae 
° * 
[Fuly 16, 1885 
we should reverse or alter the meaning of a number of important 
words in our language with a result that the future reader would 
not know what the words meant unless he noticed at what date 
the book was printed. The words would mean one thing if 
printed before the date of change, and another if printed after. 
“Tt is worthy of attention that even the republican Govern- 
ment of France in 1790, which adopted a new calendar, did not 
venture to change the old system in its astronomical ephemeris. 
“IT see no advantage in the change to compensate for this 
confusion. Ifastronomical ephemerides were in common use by 
those who are neither navigators norastronomers the case would 
be different. But, as a matter of fact, no one use; these publi- 
cations except those who are familiar with the method of reckon- 
iog time, and the change from astronomical to civil time is so 
simple as to cause no trouble whatever. 
““The change will affect the navigator as well as the astro- 
nomer. Whether the navigator should commence his day at 
noon or midnight, it is certain that he must determine his 
latitude from the sun at noon. The present system of counting 
the day from noon enables him to do this in a simple manner, 
since he changes his own noon into the astronomical period by 
the simple addition or subtraction of his longitude. To intro- 
duce any change whatever into the habits of calculation of unedu- 
cated men is a slow and difficult process, and is the more difficult 
when a complex system is to be substituted for a simple one. I 
am decidedly of the opinion that any attempt to change the form 
of printing astronomical ephemerides for the use of our navigators 
would meet with objections so strong that they could not be 
practically overcome. 
““The second conclusion which I wish to consider is that 
which proposes to reverse our method of assigning alge- 
braic signs to the longitudes by counting east longitudes 
as plus, and west longitudes as minus. The present 
system was adopted some forty years ago in Germany as 
being the most natural, because longitude was measured upon 
the earth by the apparent motion of the sun and stars from east to 
west, and it seemed most natural to count the direction of this 
motion as algebraically positive. This system has been adopted 
in the American Ephemeris since its origin, and all its tables and 
formulas which inyolve the application of longitudes have been 
constructed on this principle. To reverse this method will 
cause error and confusion to every one using the Ephemeris 
without, as far as I can see, the slightest compensating advant- 
ages. Iam therefore of opinion that it should not be adopted. 
“T respectfully submit that in view of these considerations no 
change should be made in the mode of reckoning time em- 
ployed in the publications of this office until, by some inter- 
national arrangement, a common date shall be fixed by all 
nations for the change.” 
Prof. Newcomb adds a list of changes in the American 
Nautical Almanac required when the astronomical day is 
reckoned from midnight. 
“Page 1 of each month: The numbers on this page being 
given for Greenwich apparent noon, the question whether they 
shall remain unchanged or be given for Greenwich apparent 
midnight will have to be decided by competent authority. 
““Page 2 of each month to correspond with the new mode of 
reckoning these numbers would be given for mean midnight, 
which would change the whole page. 
“*Page 3 of each month: Nearly the same remark applies to 
these pages as to page 2. When the change is made there will 
be a discontinuity of half a day in the comparison of the sun’s 
longitudes before and after the change. 
““Page 4 to correspond strictly to the new reckoning, the 
columns noon and midnight on this page would haye to be 
interchanged. This might lead to errors on the part of the com- 
puter accustomed to the old system inadvertently forgetting the 
change which had been made. If not made the system would 
be a mixed one. 
“Pages 5 to 12: All the numbers on these pages will be 
differently arranged when the hours are counted from midnight. 
“Pages 13 to 18: The lunar distances will have to be given 
for midnight on the first column of the left-hand pages, and for 
noon on the first column of the right-hand pages, thus reversing 
the placing of the numbers on the two pages. 
“Planetary ephemerides: These will naturally have to be 
given for midnight instead of noon, and the signification of all 
the numbers will therefore be different. There will also be a 
discontinuity of half a day in the progression of the series of 
epochs at the time the change is made. 
“* Moon's longitude and latitude: The indications of the times 
given in this part of the Ephemeris will be altered by half a day. 
Th? result would be that a computer inadvertently forgetting the 
change would take out a result half a day in error. 
“*Sidereal time of mean noon: Wherever this quantity was 
given throughout the Ephemeris it would, on the new system, 
have to be replaced by the sidereal time of mean midnizht, 
““ Transit ephemerides ; These would remain unaltered except 
the column of mean time of transit, which would be changed by 
12 hours. 
““Changes of nearly the same kind as in the planetary 
ephemerides would have to be made in giving the predictions of 
phenomena.” 
The following extract gives the gist of Commodore 
Franklin’s reply to Prof. Newcomb’s objections :— 
“*So far as the counting of astronomical time from antiquity is 
concerned, it is the argument of conservatism which desires no 
change in an existing order of affairs; yet, assenting to this 
argument, we might refer to a still remoter antiquity—to the 
time, not of Ptolemy, but of Hipparchus, the ‘founder of 
astronomy,’ who reckoned the twenty-four hours from midnight 
to midnight, just as the Conference has proposed. 
“While it is unquestionably true that some confusion may 
occur, yet the liability to it will be almost entirely with the 
astronomer, who, through his superior education and training, 
could easily avoid it by careful attention to the ephemerides he 
was using. During the years of change, before the ephemerides 
are constructed in accordance with the new method, it will only 
be necessary to place at the head of each page of recorded ob- 
servations the note that the time is reckoned from midnight, to 
call attention to the fact, and thus obviate the danger of error. 
“Tt is an undeniable fact that the educated navigator finds the 
conversion of time a simple matter, yet experience has demon- 
strated that to the mariner who is not possessed of a mathematical 
educatian there is a decided liability to the confusion which is 
so greatly deprecated by all who are interested in this subject. 
I believe that to all navigators, at least to all English-speaking 
ones, the new method will prove itself decidedly advantageous. 
“As is well known, for many years navigators kept sea 
time, by which the day was considered to begin at noon, pre- 
ceding the civil day by twelve and the astronomical date by 
twenty-four hours, The change to civil time now kept on board. 
ship was effected readily and without friction, so that the recom- 
mendation of the Conference regarding the commencement of — 
the nautical day has Jalready been largely anticipated. The ~ 
navigator is concerned not with his longitude but with his 
Greenwich time, ‘having obtained which he can take from the 
Nautical Almanac the data he seeks whether given for noon or 
midnight, and when the ephemerides shall have been made to 
conform to the new system there will be one time in common 
use by all the world. 
‘It seems to me eminently proper that the nation which called 
the Conference should be among the first to adopt its recom- 
mendations, and while it might possibly be better to wait until 
an entire agreement has been entered into by the astronomers of 
all nations, yet the fact tbat the first and most conservative 
observatory in the world has acceded to this proposal of the 
Conference would seem to be a sufficient reason why we should 
not wait for further developments. In deference, however, to — 
the views so well advanced by Prof. Newcomb, and in view of — 
the fact that the President has recently transmitted the proceed- 
ings of the Conference to Congress, as well also of the desira- 
bility of securing uniformity among the astronomers of our own 
country at least, I have suspended the execution of the order for 
the present with the view of communicating with those engaged 
in kindred work in order to ascertain their sentiments on the 
subject.” 
The replies received to Commodore Franklin’s circular 
may be summarised as follows: 
Mr. STONE, Leander McCormick Observatory— 
Change should be made completely on January 1, 1885. 
Prof. NEWTON, Yale College— 
Change desirable, may begin at once for internal use, and any 
communication from an observatory should state precisely what 
time is adopted. 
Prof. PICKERING, Harvard College— 
A general agreement more important than the mode of 
reckoning ; will follow Greenwich absolutely. 
