

SUMMARY OF CUltltKN'J KESEAllCHES KELATING TO 



3 Illuminating: and other Apparatus. 



Efficiency of Metallic Filament Lamps.* — K. A. Boustoun lias made 

 Heme measurements on the radiant efficiency of carbon, osmium, tantalum 

 and tungsten glow-lamps. By calculating the radianl efficiencies of the 

 different filaments at their marked voltage and taking the mean he obtains 

 the following results : — 



Itadiant Watts 



Efficiency, per ('audi • 



Carbon 29 3-5 



Osmium 5 - 2 1*5 



Tantalum 6-5 1-7 



Tungsten 7-5 1-0 



Reichert's New Breath Screen.f — This breath screen (fig 45) is 

 found to afford complete protection from the damage arising from the 



Pig. 45. 



warm breath of the observer, especially during the cold seasons. It 

 b not inconvenience the observer and is readily attached by means of 

 a clamping screw. 



Improved Micrometer.}— The object of this improvement, which is 



icnbed by M. Himoff, is to enable more accurate reading of themicro- 



as i.) disclose at a glance how much above or below a given 



Bize a piece may be after the micrometer has been set to a given size. 



I he ],in A slides on a guide, as shown in fig. 46. It is connected to 



pointer B which indicates on the dial C, a spring normally holding 



P°. infcer : " the low point. When the piece to be measured is placed 



i position the stem ls screwed down, pressing the piece against the pin A 



' ll "' Pointer moves to zero. The reading is then taken, and when 



''' x ' J 1 ' ' be measured to the same size it is placed between the 



Pin a and the stem, and the pointer will move up or down according to 



* J>.'- K °. v - Soc Edinburgh, xxx. (1910) pp. 555-02. 

 T « rt 8 Special Catalogue, 1910 



American Machinist, through English Mechanic, xciii. (1911) p. 147 (1 fig) 



