All signals herein required given by hand and arm shall be given from the left side of the vehicle in the following manner and such signals shall indicate as follows:

(1) Left turn. — Hand and arm extended horizontally.

(2) Right turn. — Hand and arm extended upward.

(3) Stop or decrease speed. — Hand and arm extended downward.

21 Del. C. 1953, § ?4157; 54 Del. Laws, c. 160, § ?1; 66 Del. Laws, c. 167, § ?1; 70 Del. Laws, c. 384, § ?1;