24 



CENTRAL SCIENTIFIC CO., CHICAGO. U. S. A. 



No. 388. 



No. 391. 



No. 392. 



No. 1734. 



388. PENETEOMETER, Standard, New York Testing Laboratory type. Operates on the same prin- 



ciple as the Humboldt, but is provided with stop-clock for timing the duration of the test by 

 half -second beats, and with dial graduated in 360 degrees, each of which represents "i,\ mm 

 of penetration. With adjustable weights for loads of 50, 100, and 200 grams, leveling screws, 

 adjustable platform and adjustable mirror for lighting the specimen. For full description, 

 see Richardson ' ' The Modern Asphalt Pavement, ' ' page 565 $68.00 



389. PENETEOMETEES, Electrically Controlled, -similar to No. 388, but with magnetic control, 



which entirely eliminates the personal equation. Adaptable to 1.5 or 60 second penetrations. 



Type A includes a rectifier to convert the alternating into direct current. 



No A B 



For, volts 110 A.C. 110 B.C. 



Each 175.00 150.00 



390. PENETEOMETEE, Miniature, for portable work, about half the size of the standard instru- 



ment, with same needle. Without clockwork 30.00 



391. PENETEATION NEEDLE, improved form, designed by Charles S. Reeve and Fred P. Pritchard 



of the Office of Public Roads and Rural Engineering of the United States Department of 

 Agriculture, and adopted as standard by the American Society for Testing Materials. (See 

 Journal of Agricultural Research, Vol. V, No. 24, for March 13, 1916, page 1121) 60 



392. PYKNOMETER, Barrett Type, 50 cc capacity, for specific gravity of tar and pitch. (See 



Journal of Industrial and Engineering Chemistry, Vol. V, No. 3, for March 1913, page 195) 2.00 



1734. PYKNOMETER, Hubbard's, for fluid and semi-solid bitumens, designed by Prevost Hubbard of 

 the Office of Public Roads. Consists of a heavy tube 70 mm long and 22 mm in diameter, 

 with accurately ground stopper made concave on under side. A hole 16 mm in diameter passes 

 through stopper and connects with this hollow space, permitting air to escape easily. Capac- 

 ity, about 24 cc; weight empty, about 28 grams. (See Bulletin 314, of the United States 

 Department of Agriculture) 2.00 



