146 SEC. 4. KINEMATICS, STATICS, AND DYNAMICS. 



52 9d. Model of a Link-work, by which two rods may be made 

 to rotate about the same axle with equal velocities in contrary 

 directions. A. B. Kempe, B.A. 



This and the following linkwork are described by the exhibitor in the 

 " Messenger of Mathematics," No. 44, 1874. 



529e. Model of a Linkwork, by which rods may be made to 

 rotate about the same axis with velocities proportional to 1, 2, 

 3, &c. The linkwork can also be used to divide angles into a 

 number of equal parts. A. B. Kempe, B.A. 



529g. Model of a Parallel Ruler. A. B. Kempe, B.A. 



In this ruler the upper bar is constrained to move vertically up and down, 

 and has no lateral motion. 



52 9i. Link Motion. William Howe, Chesterfield. 



The sketch was made by W. Howe, in August 1842, which was the first 

 sketch of the shifting link motion. The small rough wooden model was begun 

 by William Howe, in or about 1 838, at the Vulcan Foundry, near Warrington, 

 Lancashire, where the sectional cylinder, piston, valve, and foundation frame 

 were made, but this was not for the purpose of applying the link motion, but 

 a tappet motion. When the sketch referred to above was made, the link 

 motion was applied to that model, and all the parts of the old model that 

 could be brought in were used. The model of the twin bar link was designed 

 in 1848 by William Howe, and made by Mr. William Usher, who was on a 

 visit to William Howe at the time. 



529j. Model of Mechanism invented by a pupil of the 

 Royal School of Mines of Madrid, Dr. Horacio Bentabol, to ascer- 

 tain the direct line of a given point by means of linkage. 



Royal School of Mines, Madrid. 



A memoir by the author accompanies this model, in which all the necessary 

 details are given. 



76c. Instrument, with joint, which makes its upper part 

 movable in a horizontal plane. 



Professor Tchebichef, University of St. Petersburg. 



76d. Model of joint, which directly transforms a reciprocating 

 into a circular motion. 



Professor Tchebichef, University of St. Petersburg. 



530. Drawing and Model of a connecting motion between 

 two shafts turning in reverse directions. Charles Bourdon. 



530a. Pour Models, for the description of tooth -profiles, and 

 lines of contact. 



Royal Rhenish Westphalian Polytechnic School, Aix-la- 

 Chapelle. 



No. 1 illustrates the construction of general toothing, according to Reu- 

 leaux's method. 



