It was her purpose to tell her and to swear to her most solemnly,--should she find her preparing herself to leave the house after six in the evening,--that she should be kept out the whole night, having a purpose equally clear in her own mind that she would break her oath should she be unsuccessful in her effort to keep Ruby at home. 
 decided to tell Ruby most solemnly, if she found her preparing to leave the house in the evening, that she should be kept out the whole night. 