January, 19o6.] Reinforced Concrete in Construction. 41

Bui lding Inspect ion, and changes in the same prompt ly re- ported.

(d) The Chief of the Bureau of Bui ld ing Inspec t ion may require full tes ts to be repeated on samples selected f rom the open market , when, in his opinion, there is any doub t as to whe ther the product is up to the s tandard of these regulat ions, and the manufac turer mus t submi t to the Bureau of Bui lding Inspec- t ion once in at least every four m o n t h s a certificate of tests showing tha t the average resistance of th ree specimens to cross b reak ing and c rush ing are not below the r equ i rement s of these regulat ions. Such tes ts mus t be made by some labora tory ot recognized s tanding on samples selected by a bui lding inspector or the l abora tory , f rom mater ia l actually go ing into the con- s truct ion, and no t on ones furnished by' the manufacturer .

(e) In case the results of tes ts made under these condi t ions should show tha t the s tandard of these regula t ions is no t maintained, the approval of this bureau to the manufac ture r of said blocks will at once be suspended or revoked.

Tests made under the requ i rements of the City of Phi ladelphia on concrete blocks in the marke t here have developed about the fol towing resu l t s '

Modulus of rupture, I5o to 175 pounds. Compress ive s t rength , 12oo to 16oo pounds per square inch. Absorpt ion , 5 per cent. The compress ive s t reng th is reduced little, if any, by the wate r ab-

sorbed. F reez ing tests show little loss. The average compres s ive s t r eng th af ter f reezing is in the vicinity of

tooo pounds per square inch. The blocks passed the fire tes t s well.

A io, ooo H O R S E - P O W E R S T E A M T U R B I N E .

The two s team turb ine sets of io,ooo horse -power each, which are be ing installed at the Rhenan i an Wes tpha l i an Electr ici ty Works , are the la rges t turbine sets, and in fact the largest s ta t ionary engines of all Europe. Each of these gigant ic engines comprises a tu rb ine r unn ing at I,Ooo r. p. m., which is d i rec t -connected to a ro ta ry cur ren t ~ gene ra to r of 5,ooo kilowatts, 5,ooo volts, and 5o periods per second, as well as to a d i rec t -cur ren t genera- to r of 1,5oo ki lowatts and 6oo volts, and to a central ' condensing plant. The whole set is 2o meters in length, and weighs I9o tons, of which 9.4 meters and lO7 tons co r respond to the turbine. T h e m ax imum he igh t of the tur - bine above the floor is 2.6 meters . The turbine is of the single-cylinder type, and has only two bear ings , one of which serves at the same t ime as a bear ing to the a l te rna tor . The gove rno r is made to compensa te to x per cent. of any oscil lat ions in the angular speed, with var ia t ions in the load as h igh as 20 per cent., while the m ax i m um var ia t ion in the n u m b e r of revo- lut ions be tween r u n n i n g at no load and at full load is no t to exceed 5 per cent. A n o t h e r unit of the same size is short ly to be installed at the power s ta t ion in a Wes tpha l i an min ing company.--Scienti~c American.