It was not till the time of Halley's comet, 1682, that modern astronomy began to consider the question of the possibly periodic character of cometic motions with attention.
The comet of 1680, called Newton's, was the very first whose orbital motions were dealt with on the principles of Newtonian astronomy, and Halley's was the first whose periodic character was recognized.
Most girls get their first inkling of the menstrual period from the periodic "sick spells" of mother or sister.
If women are to demand equal opportunity and equal pay, they must be able to do equal work without periodic times of illness.
Nevertheless, the whole group of six noble gases, from helium to emanium, were discovered and fitted into the periodic system at a place where nobody had suspected a gap.
In former years, it is said, the club had kennels at Bullingdon, and held periodic hunts there; and it is still largely composed of hunting men.
The value of any element of the planet's motion will generally be represented by the sum of an infinite series of such periodic quantities, having different periods.
The relation between the periodic time of a planet and its mean distance, approximately expressed by Kepler's third law, follows very simply from the laws of centrifugal force.
The most interesting kind of periodic inequalities are those known as "terms of long period.
The periodic variations can be represented algebraically as the resultant of a series of harmonic motions in the following way: Let L be an angle which is increasing uniformly with the time, and let n be its rate of increase.
The periodic time varying inversely as n, this equation expresses Kepler's third law.
In the child, asthma is usually periodic in its recurrence, but as he ages it tends to become more erratic in both its manifestations and time of appearance.
These already suppose that the observed mechanical processes of the circular or periodic type, like the revolutions and rotations of the stars, are incidents in a historical mechanical process of a larger scale.
However, the attention to sentence-structure necessary in order to make it periodic is a thing devoutly to be wished at this stage of growth.
Is the first sentence of the paragraph beginning in the middle of page 36 periodic or loose?
With this danger removed, the result of the generous use of periodicsentences will be nothing worse than a too obvious preparation.
The philosophy of the periodic sentence has been best stated by Herbert Spencer.
Theoretically the periodicsentence is better than the loose sentence; for it economizes attention.
There is no other remedy for careless, slipshod sentence-making so effective as the construction of many periodic sentences.
In the eighth sentence of paragraph 21 is the structureperiodic or loose?
There is, however, a reason why young persons should be encouraged to use periodic sentences.
Closely connected with the emphasis gained by the periodic arrangement of the parts of a sentence is the emphasis gained by forcing words out of their natural order.
In the paragraph filling pages 79 and 80 there are many examples of periodic and parallel structure.
Spencer, Herbert, on the philosophy of the periodic sentence, 212.
They are not, usually, periodic in any regular manner, but they have the same tendency to complete intermission, and they frequently haunt some one or more definite nerves for a considerable period of time.
Without periodic depression, apparently, a man never gets as close to the heart of life as he otherwise would.
It is all the more surprising, then, to have many passages in his letters refer to periodic attacks of depression.
In people who suffer from periodic fits of depression it is not unusual to find that in the early morning the pulse is not more than fifty-five.
Sidenote: Catalogues and indexes} The law directs that the Register of Copyrights "shall print at periodic intervals a catalogue of the titles of articles .
Although it is a still further digression from the main purpose of this paper, I must permit myself a few words on another point relating to the strictly medical claims of the plan of "universal periodic medical examination.
Everybody ought to understand that trade varies in activity, from time to time, in a periodic manner.
It was one of those periodic crises which, occurring throughout a whole century, succeeded in momentarily eclipsing the splendor of the Faith and in almost disrupting the structure of its organic institutions.
I should, however, say that the moon is not the sole agent engaged in producing this periodic movement of our waters.
The periodic time of each revolution, and the mean distance at which that revolution was performed, will be always connected together by the formula of Kepler.
The tidal consequences which we have already demonstrated are emphatically of this non-periodic class--the day is always lengthening, the moon is always retreating.
Each "tide" is a simple periodicrise and fall, and we can compute for any future time the height of each were it acting alone.
But these periodic phenomena, however important they may be to us mere creatures of a day, are insignificant in their effects on the grand evolution through which the celestial bodies are passing.
Indeed, I am here only stating what every one is familiar with under the form of Kepler's Law, that the square of the periodic time is in proportion to the cube of the mean distance.
But, further, in availing yourself of this divine resource amid the daily exigences of life, why should you wait always for the periodic season and the formal attitude of prayer?
One can easily visualize a stream coursing the early Permian landscape that was subject to periodic flooding and droughts.
Analogous facts have been given with respect to the nyctitropic and periodic movements of plants.
From the course pursued on the second day, when the plant had accommodated itself to the light from above, there cannot be much doubt that the leaves undergo a daily periodic movement, sinking during the day and rising at night.
In a large majority of the genera, namely, 24, the movement is a rising one; so that the same direction prevails in these nyctitropic movements as in the lesser periodic ones described in the second chapter.
It was equally evident that the cotyledons of many plants, not provided with pulvini, increased rapidly in length; and their periodic movements no doubt were exclusively due to growth.
Disturbance of thePeriodic Movements of Cotyledons by Light.
Therefore the periodic movements of the cotyledons of 'O.
These are partially reflected in theperiodic misunderstandings between the Western world and Japan.
Our plans for periodic briefings, which we had originally set up with ADC, had suffered a bit in the summer because we were all busy elsewhere.
If the theory of the periodic decay of all created things, he urges, be scientific, it must be universal, and so true of all the other states as well as of the ideal.
It is now known that the Blue Nile, flowing out of the mountainous parts of Abyssinia, is the sole cause of the periodic overflow of the Nile.
In a table accompanying Koenigsberger's paper the elements are arranged upon the periodic system and the atomic susceptibility (product of specific susceptibility into atomic weight) is given for each.
The difficulty in these investigations is that we are dealing with a small effect, and a very long series of data would be required satisfactorily to eliminate other periodic influences.
The truly spectacular manifestation of pollution in the metropolitan Potomac is the periodic growth of algae there in summertime.
The bulk of it is released in periodic surges when local rainstorms overload the old-fashioned combined sewer systems of the District of Columbia and Alexandria.
