This apparatus is for the study of wave by a string. Alike the meld experiment, the length of this apparatus is 150cm. and 34cm. in height. The current generator uses current of 220V A.C. 50Hz. The distance between the box and the pulley is 100cm. The rope which is tied across the pulley, at one end it is tied to a frequency generator box, and at the other end it is ties to a plate 29g. in mass, in which there are 300g. in mass for experiment. (6x10g. and 12x20g.) This apparatus can be used to test the speed of the wave on the rope and find the frequency from the frequency generator box.