SCIENCE— ADVERTISEMENTS 



J Sign of Quality W&MS. /^o'" « ^^"^e o/ ^^ 



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No. 905 tJNIVERSAl, MOT(«a ROTATOR. This rotator has been designed especially for school 

 and laboratory use. The motor will run on either A.C. or D.S. of 110 volts. The speed may be 

 varied from a few revolutions per minute to 1,500 R.P.M. The speed changes are continuous— not 

 in steps — and speed is changed by simply turning a thumb screw. The holder for the accesories 

 IS standard torm and eize and will hold all commonly used accessories. A chuck is included with 

 the instruments for holding discs, etc. The position of the rotating shaft may be made horizontal, 

 vertical or any intermediary position and may be held firmly in 

 any of the positions. The use of the friction disc eliminates all 

 jerklness of starting and running. The motor is especially adapted 

 for the purpose and ie very powerful and will pull any accessory 

 at full speed. A stop is provided so that excessive speeds are not 

 possible, although sufficient speed is provided for to operate all 

 rotator accessories. A speed counter is mounted so that the R.P.M. 

 may be determined where quantitative work is required. The 

 entire apparatus is about 30 cm. long, 15 cm. wide and 20 cm. high. 

 Handsomely finished in black enamel and nickel-plated trimmings. 

 Complete as described with 6 feet of cord and detachable plug for 

 connection. 



W. M. Welch Scientific Company 



Manufacturers, Importers and Exporters of Scientific Apparatus 

 1516 ORLi£:A.]NS STREET CHICAGO, ILL., U. S. A. 



"We shall be pleased to send to science departments of schools outside of the United States 

 our especially prepared catalogue for foreign circulation only. A request giving your official posi- 

 tion is all that is necessary in order to receive this catalog. 



