No. 51911. 



Wedge, Screw, Equilibrium. 



273 



51 909 A. 1:5. 



51 906. 1 : 6. 



51 910. 1:10. 



51 911. 1 : 9. 



51.904. 26 Double-hook Weights for Hartl's Wedge Apparatus 



Those weights can also be used for the experiments on levers, for the parallelogram of forces, etc. 



51.905. Wood Cylinder, with paper surface, Figure, for showing the formation of the 



screw line (Fr. phys. Techn. I, 2, Fig. 2013) 



51.906. Screw Apparatus (Frick's) for demonstrating the action of the screw, Figure (Fr. 

 phys. Techn. I, 2, Figs. 2219, 2220 [I, Fig. 130]), without weights 



51.907. -- idem, on stand, cf. Fig. 51,908, with loading weights and with one screw . 



51.908. -- idem, with 2 screws of different pitch, Figure 



s. d. 

 1. 6.0 



0. 3.0 



2. 0.0 

 2. 0.0 



2.10.0 



51.909. Screw Apparatus (Hartl's), Figs. A and B, for the formation of the helical line 



and the mode of action of the screw (Ztschr. f. d. phys. u. chem. U., 15, 1902, p. 318) j 2.15.0 



The cylinders forming the female thread are fixed to a base comprised of wood fillets, it being 

 possible to unwind the base. 



51.910. Screw Apparatus (Grimsehl's), Figure, for explaining the action of physical forces 



on the modus operandi of the screw (Ztschr. f. d. phys. u. chem. U., 17, 1904, p. 132) ; 3. 5.0 



51.911. Equilibrium Apparatus, for explaining stable, unstable and indifferent equilibrium 



(Fr. phys. Techn. I, 2, Fig. 2108) 0.12.0 

 By placing the spheres upwards or downwards stable or unstable equilibrium can be produced. 



Models of Screws: see Section 

 'Models of Machines and Machine Elements". 



Cl. 3303, S304, 3f,05, 

 3306, 5529, 589. ] 8 



