SCIENCE-ADVERTISEMENTS 



ACCELERATION APPARATUS 



NO. MM852— FALLING BODIES 

 New and Improved Form 



This instrument is used to verify the law of falling bodies. It is designed par- 

 ticularly for use with college and university' texts in which a very high degree of 

 accuracy is possible and errors due to mechanical imperfections have been practi- 

 cally eliminated. The apparatus in itself is similar in make to our No. 8S2A, but its 

 accuracy is much greater, due to the additional care as to methods of eliminating 

 friction. 



The carriage which carries the tuning fork is held between two upright highly 

 polished nickel plated rods. These rods are about 170 centimeters in height, and 

 are mounted on a heavy tripod base with leveling screws. 



The tuning fork which is carried on this mounting is provided with a coil and 

 contact maker and binding posts, and is electrically driven, so that the same ampli- 

 tude of vibration is assured during all the time of, fall. The exact crest of wave 

 may, therefore, be more accurately located, even at the bottom of the plate. 



The method of mounting the carriage within the space between the glass rods 

 eliminates friction almost entirely. The glass plate is made of heavy plate glass 

 and is mounted by a method holding it securely in position and yet enabling it to be 

 very easily removed. It may also be moved sidewise and thus allow several curves 

 to be traced on the same glass plate. 



Two dash pots are provided on the base of the instrument to catch the descending 

 carriage and absorb the jar, and make it more lasting. 



An additional feature of this design is the possibility of fitting a ball-bearing pul- 

 ley at the top. This enables determining the law of falling bodies with a diminished 

 rate in acceleration. This causes the rate of travel of the carriage to be very much 

 less. This enables the partial counterbalancing of the carriage on the opposite side 

 of the pulley. A weight which counterbalances the fork and carriage may be pro- 

 vided and an adjustable platform is arranged so as to add sufficient weight to pro- 

 duce uniform motion at any part of the path of descent of the carriage. 



The apparatus is used in many universities and college laboratories and proves the 

 best of its kind for dealing with measurement of "g." The percentage of errors 

 will not amount to more than 2%. In many cases it is less than 1% with careful 

 determinations. The high accuracy is due to the almost complete elimination of 

 friction. All parts are adjustable and furnish all possible latitude for making all 

 tests that may be needed. 



The apparatus is complete with electrically driven tuning fork, contact maker, and 

 glass plate. It is made of tbe very best material and contains the best workmanship 

 and is very durable. Handsomely finished in black enamel and nickel plated rods 

 and trimming. With instruction sheets. 



This apparatus is part of that specified in Millikan & Mill's "Electricity, 

 Sound and Light." and Millikan's "Mechanics, Molecular Physics and 

 Heat." We can supply you with all o'f the equipment for these texts and 

 have prepared lists specially for the required equipment for these texts. 

 Copies of these lists sent upon request. 



MM352 



MM852A— ATWOOD'S ATTACHMENT for No. MMS52 Accele 

 a counterbalance weight, extra weight for use as 1 

 is mounted on ball bearings. The assembly of the 



ation Apparatus. Consists of a light aluminum wheel, 

 :der and an adjustable platform. The aluminum wheel 

 e parts is shown on the illustration No. MM852B. 



MM852B— ACCELERATION APPARATUS AND ATWOOD'S MACHINE, combined. Consists of No. MM852 and 

 No. MMS52A. Complete as shown. 



MM85ZC— EXTRA GLASS PLATE about 15 x 140cm. for No. MJIS52 or No. MM8S2B. 



A Sign of Quality 



P- SERVICE 



A Mark of Service 



W. M. WELCH SCIENTIFIC COMPANY 



Manufacturers, Importers and Exporters of 

 Scientific Apparatus and School Supplies 



1516 Orleans Street 



Chicago, m., U. S. A. 



