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.