The fewactinometer observations will be found in another part of the Appendix.
The few actinometer observations which I was enabled to record, were made with two of these instruments constructed by Barrow, and had the bulbs of their thermometers plunged into the fluid of the chamber.
The actinometerconsists of a large cylindrical thermometer bulb, with a scale considerably lengthened, so that minute changes may be easily seen.
To take an observation, theactinometer is placed in the shade for one minute and read off; it is then exposed for one minute to sunshine, and its indication recorded; it is finally restored to the shade, and its reading noted.
For those photographers who are in the habit of using an actinometer giving the plate speeds in H.
With daylight, however, the light is constantly fluctuating, and this renders the use of an actinometer a necessity for correct exposure.
An actinometer must be used to gauge the amount of exposure, as only a faint image, and in some tissues none at all, is visible during or after exposure.
We then shift the paper in the actinometer so as to get a fresh portion under the tissue strips, or we substitute a new piece.
We refill the printing frame and print again until the actinometer registers one, two, or three more steps and letters, and then try again.
Now refer to the actinometer and see what has taken place on the silver paper which we put into it.
But there is this advantage now, as then, that if some convenient form of actinometer be used to test the light, we are able to judge at once, what speed of plate will be necessary to deal with each subject as it arises.
The judgment of the operator must be brought into play and no actinometer will be of much use under the varied conditions which are the rule, not the exception.
The single transfer process may be briefly described as follows:--The sensitive tissue is exposed under a negative and the exposure gauged by actinometer as for double transfer printing.
Sir John Herschel also designed an instrument for observing the heating power of the sun’s rays in a given time, to which the title Actinometer is given.
The actinometer indicated an exposure of thirty seconds where in good light one would be right.
When you get home, the first thing to do is to get hold of a paint box and paint the underside of the glass of your actinometer to match the darkened paper.
You may sometimes find that theactinometer indicates a very different exposure from what the eye would lead you to expect.
The table tells us what the exposure would be with this stop on this view, on a bright day; and if the actinometer take twenty seconds to reach the painted tint, then we must double the exposure given in the table.
We can, however, by chemical means arrive at an exact estimate of the active power, and for this purpose an actinometer is used.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "actinometer" in a variety of sentences. We hope that you will now be able to make sentences using this word.
