FEBRUARY 7, 1907] 
WA TORE 3 
but through muscular activity and the exercise of our 
senses. Accordingly, a healthy and timely growth and 
development of the brain is to be promoted by an educa- 
tion involving a great variety of activities, skilfully 
adjusted as to quality and quantity to the mental and 
physical status of the child. 
Closely related with this of brain culture is the subject 
of manual training, which has recently gained a foot- 
hold in our scheme of rational education. Its nature and 
educational value are still under discussion. 
The manual-training movement stands inevitably as a 
criticism upon the system of education which came down 
the ages through the fathers to us, and naturally the 
latter stands on the defensive. It also is a standing re- 
proof to the old wasteful, unscientific method of teaching 
apprentices the theory and uses of tools. It is for educa- 
tional science to justify the ways of progress, which lays 
aside the idols of the past and erects new temples and 
opens new kingdoms. Of all the temples, none is finer, 
none is more glorious, and none should be more scientific- 
ally planned and reared than education. 
The evolution of the fully fledged technical school, or 
the technical department of the university, has taken place 
during the last half-century, and yet its broad, stimulating, 
attractive features have a following which bids fair to 
double the attendance of college and university students. 
This does not mean that letters and polite learning are 
being neglected, but that a new constituency is eager for 
the new education. This new education, though it recog- 
nises at all points a high order of usefulness, and contains 
little that is conventional, is only remotely professional. 
If ever its curriculum becomes narrow, it is quickly con- 
demned by the best representatives of an education which 
combines utility with culture. No longer can_ the 
““Levites of culture,’’ as Huxley calls them, claim to 
monopolise liberal education. The new education can be 
as liberal as the old, and both can be narrow. Fortu- 
nately, they flourish side by side, and the future shall 
choose the excellences of each. An adequate science of 
twentieth-century education will evaluate the characteristics 
of each, and bring the wisdom of the past, not its foolish- 
ness, to nourish the wisdom of the future. 
Accuracy oF ASTRONOMICAL CLocks.? 
The accuracy with which our astronomical clocks per- 
form their function is a subject of interest. The 
earliest star catalogue of precision is that of Bradley. In 
discussing the performance of his clock, I have used the 
adopted rates as given by Auwers in his re-reduction of 
Bradley. The monthly means of the rates from July, 1758, 
to July, 1759, were taken, and the difference of each rate 
from its monthly mean. Then the mean of these differ- 
ences, without regard to sign, was taken for each month. 
The rates of two other clocks of the Greenwich Observ- 
atory were likewise discussed, the standard clock for the 
year 1850 and that for 1900, the adopted daily rates as 
published in the annual volumes being used. The first of 
these was kept in the observing room, and thereby sub- 
jected to large variations of temperature, while the second, 
made in 1871 by E. Dent and Co., was fixed to the north 
wall of the magnetic basement, as in this apartment the 
temperature is kept nearly uniform. The pendulum of this 
latter clock is provided with barometric as well as thermo- 
metric compensation. 
There are two well-known clocks which should be men- 
tioned, and in conclusion I will give some hitherto un- 
published data concerning the clock with which I have 
been working during the past three years. 
Probably no clock has had its rate. more thoroughly 
discussed than Hohwii No. 17, the standard clock of the 
observatory at Leyden. It was set up in the transit room 
in 1861, and in December, 1898, was removed to the large 
hall of the observatory, where, enclosed in two wooden 
cases, it was placed in a niche cut in the pier of the 
1o-inch refractor. Further, to guard against sudden 
changes of temperature, the niche is closed by a glass door. 
At the meeting of the Royal Academy of Sciences at 
Amsterdam, held September 27, 1902, Dr. E. F. van de 
Sande Bakhuyzen submitted a formula as the best repre- 
1 From an address delivered by Prof. W. S. Eichelberger chairman of 
the Section of Mathematics and Astronomy. 
NO. 1945, VOL. 75] 
sentation of the daily rate of the clock, and gave the result 
of a comparison of the observed daily rates 1899-1902, the 
average interval of time for each rate being six days, with 
those computed by means of the formula. I find that 
during the year 1900 the mean of these differences 
0-028s., and the largest difference is 0-071s. 
About 1867, F. Tiede installed at the Berlin Observ- 
atory a weight-driven clock enclosed in an air-tight case. 
The original escapement was replaced in 1876 by a gravity 
escapement, and the clock continued to give satisfaction 
certainly up to 1902, when it was dismounted for clean- 
ing. The only published rates that I have been able 
to secure are those during twelve weexs in 1877-8. During 
this period the average deviation of the observed daily 
rates, the average interval for each rate being six days, 
from the mean daily rate for the entire period is 0-030s. 
In 1903 there was installed at the U.S. Naval Observ- 
atory one of Riefler’s clocks, No. 70, with a nickel-steel 
pendulum, the impulse being communicated to the pen- 
dulum through the suspension spring. This clock was 
enclosed in an air-tight glass case, and was mounted in a 
vault where the temperature was artificially controlled. 
The definitive rates have been determined from September, 
1903, to May, 1904, but, unfortunately, during this entire 
period we were unable to prevent the glass case leaking, 
and there was a variation of temperature in the vault of 
about 5° C. 
Collecting together the results obtained, we have :— 
Mean Deviation of Daily Clock Rate. 
is 
Clock Date Mean Deviation 
Bradley ... nc ocd 1759 "102 
Greenwich Observatory 1850 0'149 
Greenwich Observatory 1900 OOS 
Berlin Observatory 1877 0°02-0'03 
Leyden Observatory ... 1g00 0°028 
U.S. Naval Observatory 1904 O'OI5 
Fact AND THEORY IN SPECTROSCOPY.* 
Any treatment of the production of radiation falls more 
or less naturally into three parts, namely :—(1) the radiation 
of solid and liquid -bodies which is almost, but not quite, 
independent of atomic structure; (2) the radiation which 
takes its rise in radio-active substances, and which is 
apparently dependent upon atomic collapse; and (3) the 
radiation of gaseous substances, dependent almost entirely 
upon normal atomic structure, and possibly also upon the 
mode of excitation. 
The subject to which consideration is now invited has 
to deal only with radiation of this third class. Radiation 
which in terms of the electron theory is said to be due, not 
to abrupt or discontinuous acceleration, but to periodic 
acceleration. 
Briefly defined, spectroscopy is that science which has 
for its object the general description of radiation, including 
the production of radiation, the analysis of radiation, the 
registration of radiation, and the measurement of radiation. 
The theory of separating, recording, and comparing 
radiation is by no means simple or complete. That these 
last three operations demand in practice the highest degree 
of skill is exemplified by the work of Rayleigh, Rowland, 
| Michelson, Perot and Fabry, and Hale. 
There is, however, a certain very true sense in which 
these last three processes are merely preparatory to a more 
profound study of the first, namely, the production of 
radiation. From this point of view, spectroscopy hinges 
upon the radiant atom—if there be an atom—and may be 
| defined, imperfectly and narrowly perhaps, as the science 
of the vadiant atom. 
More than one brilliant and partially successful attempt 
has been made within the last quarter-century to establish 
an adequate foundation for this science by devising what 
may be called a satisfactory atom. But before consider- 
ing any of these attempts, it may be well to state briefly 
what seems to be the criteria by which any such found- 
ation is to be judged. 
Perhaps it may be fair to consider that atom as most 
competent which will explain satisfactorily the largest 
number of the following nine facts :— 
1 From an address delivered’ by Prof. H. Crew, chairman of the Section 
of Physics. 
