The inhabitants of tropical America sometimes keep fireflies in small cages for purposes of illumination, or make use of the insects for personal adornment.
The divisions of both drums are conveniently read, simultaneously, by the lens e; at night the lamp which illuminates the webs and the position-circle also illuminates the drum-heads (see on illumination p. 385).
In greenhouses where plants requiring very different optimum temperatures and illumination are kept together.
Cases of pallor due to too intense illumination and destruction of chlorophyll must also be distinguished.
The process of augmenting the resultant illumination at a particular point by stopping some of the secondary rays may be carried much further (Soret, Pogg.
When the difference of phase amounts to A, we may expect the resultant illumination to be very much reduced.
In any case the proportion of the whole illumination to be found outside the circle of radius r is given by J02(z)+J12(z).
For the dark rings Ji(z) =o; so that the fraction of illumination outside any dark ring is simply Jo 2 (z).
In estimating theoretically the resolving power on a double star we have to consider the illumination of the field due to the superposition of the two independent images.
The illumination at B due to P then becomes comparatively small, indeed for some forms of aperture evanescent.
The only effect of the ruling is to diminish the amplitude in the ratio a: a+d; and, except for the difference in illumination, the appearance of a line of light is the same as if the aperture were perfectly free.
On either side of any one of them the illumination is distributed according to the same law as for the central image (m = o), vanishing, for example, when the retardation amounts to (mn t 1)X.
The expression (5) gives the illumination at due to that part of the complete image whose geometrical focus is at =o, the retardation for this component being R.
As the point P is more and more deeply immersed in the shadow, the illumination continuously decreases, and that without limit.
If the slit is of 'constant width and we require the illumination at various points on the screen behind it, we must regard the arc of the curve as of constant length.
Outside the cone of 54° there will be faint illumination; within it, no secondary rays will be transmitted to the eye.
Teacher had been with me nearly two weeks, and I had learned eighteen or twenty words, before that thought flashed into my mind, as the sun breaks upon the sleeping world; and in that moment of illumination the secret of language was revealed to me, and I caught a glimpse of the beautiful country I was about to explore.
They do not see that the role of the natural sciences in this matter is merely to serve as an instrument for the illumination of one side of it.