554 SUMMARY OF CURRENT RESEARCHES RELATING TO 



by the anger, pressure upon this collar controls the column of liquid. 

 If it We desired, on the other hand, to alter the size of the cm ity within 

 the collar, independently of the column of liquid, the top opening of the 

 pipette is left free. 



Method of Examining' Faeces for Evidences of Parasitism.* — M. C. 

 Hall, after describing methods of other observers, states that the besl 

 results in routine examination of faeces of all kinds are obtained as 

 follows. Briefly, the method consists in breaking up the faeces very 

 thoroughly by shaking in water, adding a quantity of small shot if ne- 

 cessary or desirable ; sieving through a set of brass sieves and then 

 through a silk bolting-cloth sieve, or a sieve made with a jeweller's fine- 

 meshed brass screen ; examining the material left on sieve for parasites ; 

 sedimenting (and washing) ; centrifuging (and washing) — one tube being 

 filled with calcium chloride solution of 1250 sp. gr., centrifuged and, if 

 desired, the top cubic centimetre removed with a pipette, shaken up in a 

 tube with 14 c.cm. of water and centrifuged — and then making a micro- 

 scopic examination of a drop of the sediment from the bottom of the 

 tube centrifuged with water, and one from the top when the calcium 

 chloride solution alone was used, or from the bottom in case water was 

 added to the top cubic centimetre. The material is washed at either or 

 both of the points indicated. 



R. and J. Beck's Grinding and Polishing Machine for making 

 Microscopical Specimens for Metallurgical Work.f — This machine, 

 the details of which have been worked out- in conjunction with some of 

 the leading metallurgists, gives in a compact and convenient form all 

 that is required for preparing metal specimens for examination. 



Fig. 69 gives a general view of the machine, which consists of a 

 vertical spindle carrying a grinding or polishing disc driven by a small 

 electric motor. The spindle A is made of steel, and is bored out at the 

 upper end to receive the disc upon which the polishing or grinding 

 material is to be placed. The lower end is hardened to prevent undue 

 wear. This spindle is furnished with a speed cone F with pulleys of vary- 

 ing diameters, and is driven by means of a belt from the driving cone G, 

 which in its turn is driven from the motor. By shifting the belt on the 

 speed cone a range of speeds varying from about 300 to 1,000 revolutions 

 per minute can be obtained. The disc B is made of brass, and fits by 

 means of a tapered fitting into the spindle A, which allows of its easy 

 removal, and at the same time ensures accuracy in the running. A lip 

 E projects downwards and prevents any grinding or polishing material 

 reaching the bearing. 



The cloth for polishing, or emery-paper for grinding, is secured to the 

 disc by a simple but very effective device. A groove K is made in the 

 edge of the disc, and the paper or cloth is stretched over the surface of 

 i In' disc, ami is held in position by means of a garter made of a stiff brass 

 spiral spring, which presses the material into the groove. In this way the 

 cloth or paper is held in close contact with the disc, no matter what its 

 thickness may be. 



* U.S. Depart. Agric, Bull. No 135 (1911) 36 pp. (figs.). 

 t R. and J. Beck's Special Catalogue (1911) (2 figs.). 



