Every witness shall be exempt from arrest in civil actions or special proceedings during his attendance at any court, or before a commissioner, arbitrator, referee, or other person authorized to command the attendance of such witness, and during the time such witness is going to and returning from the place of such attendance, allowing one day for every thirty miles such witness has to travel to and from his place of residence. (1777, c. 115, s. 44, P.R.; R.C., c. 31, s. 70; Code, s. 1367; Rev., s. 1644; C.S., s. 1808.)