-FOR REI.EASE 
NEW DUMVILLE DEVICE SUBSTITUTE FOR GEIGER COUNTER AS DEMONSTRATOR 
THE HEINBJCH ACTINOSCOPE 
A national association of physics teachers received with great 
enthusiasm Heinrich* s demonstration of his newly discovered ac- 
tinoscope. The Heinrich Actinoscope uses the property of gas 
discharge tubes under the influence of ionizing radiation to 
accomplish its interesting feats for class room deHionstration 
purposes. Mr. S. H. Dumville, an old friend of the inventor, was 
delighted when the inventor without solicitation on the part of 
the Dumville Manufacturing Company offered this Instrument firm 
the honor of exclusive development, production, and sales rights 
to the fascinating device. 
DUMVILLE MFG. CO. 
-A company whose 
controlling stock 
is owned by teachers 
-A company dedicated 
to the defense of the 
free peoples of the 
world and the defense 
of America 
-A company dedicated 
to furthering ideals 
of American education 
A tube of a higher firing potential is used as the receiver, s^hen 
exposed to ionization radiation it will show through a network 
of electronic canponents the presence of such radiation by caus- 
ing another indicator to demonstrate the presence of the radia- 
tion. By proper shielding this can be achieved for a selected 
WAND-TIPE HEINRICH ACTINOSCOPE 
The Heinrich Actinoscope is not designed for quantitative work but as a demonstrator. 
This must be kept in mind in discussion with students. Experimentation has not shown 
it useful as a detector for mineral ore sources, though the company believes that fur- 
ther research and improved circuitry might make it at least valuable in this area for 
demonstration use. The actinoscope differs from all published works prior to its intro- 
duction in principle. Attempts to produce this type of indicator are reported as early 
as 1934. It is doubtless desirable to include in a general science or general physics 
course a demonstration of X-rays. Colleges may often obtain an X-ray machine literally 
for the asking from commercial suppliers. However, the effectiveness of the demonstra- 
tion is sharply reduced by the difficulties encountered in proving the existence 
of invisible radiation. 
The classical detector is the electroscope whose discharge serves as an indicator for 
the presence of ionizing radiation. However, in damp weather an electroscope discharges 
anyhon; and the embarassed instructor has to give a sales talk concerning the increased 
speed of discharge. Outside of this difficulty the electroscope is, as a rule, a small 
instrument not readily visible in a large audience or class assembly. Projection of 
the electroscope deprives the demonstration of its directness. Applying the fluores- 
cence of a suitable substance as a detector is not strikingly strong and requires too 
a certain time for visual accomodation, at lea,st for the majority of observers. Photo- 
multipliers can be used to increase the effect, but here again the directness of the 
demonstration suffers. The vast majority of American colleges shy away from expensive 
geiger type detectors which can be used only a few times per year. Also with geiger 
type devices an ever present effect has to be discounted which effect is at least to 
the novice not always convincing. Other devices require extensive secondary equipment 
such as iCBiization chambers, dosimeters, color changes, PH changes, resistance changoq 
and photographic effects. 
The actinoscope is a cheap, self contained, fairly rugged, and dramatic demonstration 
device. For its specific use, it does not necessarily have to be quantitative; in fact 
it could be considered an advantage if it were alternative, that is reacting to radia- 
tion above a certain level in one way, and to less or no radiation in an other way. 
In operation the receiving end of the actinoscope is placed near an ordinary X-ray tube. 
The high voltage current is applied to the X-ray tube. The instructor immediately has 
a dramatic and highly interesting effect produced in full view of his whole class. It 
is very interesting to obtain an actinoscope and expose it to this type of radiation. 
The Dumville Manufacturing Company believes that there is a large field of development 
oj)en for those who are interested in indicators for other electromagnetic oscillations. 
Shields can be found which are on the one hand selective enough and on the other hand 
compatible with the functioning of the actinoscope. The company solicits inquiry as 
well as sharing of any discoveries with those who experiment in its use. 
DUMVILLE MANUFACTURING COMPANY 
• o* ss.s • riiiNDSNir niignts 
WASHINGTON 1., 0, C. 
At th. natlon’t 
liMtrunwnt Oltr 
