The instruments executed to the railroad company by Trammell and his sureties do not constitute a release, but the contract is a covenant not to sue the Houston & Texas Central Railroad Company on account of the injuries received, and such contract did not have the effect to discharge Robertson from liability to Trammell. Chicago v. Babcock, 143 Ill., 358, and see 58 L. R. A., 299, where the authorities are collected. Giving an indemnity bond to the railroad company did not change the character of the transaction.

For the reasons stated the’ application for a writ of error is refused.