This 'Hydarium' of Northamptonshire is found in a Peterborough Cartulary (Cott. MS. Vesp. E. 22, fo. 94 _et seq._). It is drawn up Hundred by Hundred, like the surveys of Leicestershire and of Lindsey, and is, therefore, probably connected with the assessment of Danegeld. Although it is of special value for reconstituting the Domesday Vills, the assessment it records so often varies from that which is found in Domesday that we cannot institute a close comparison. The introduction of a 'parva virgata' further complicates the reckoning. That the original document was written on a roll is shown by the use of the phrase 'per alium rotulum'. The statement on fo. 97_b_ that there ought, at one place, to be half a hide more 'per rotulos Wyncestr[ie]', would seem to refer to Domesday; but on the next page we read: In Pytesle Abbas de Burgo v. hid. [et] dim. set tamen in Rotulis Wyncestr[ie] vi. hid. et iii. parvas virgatas. Since Domesday records this holding as 'v. hid. et una virgata terræ', the reference (if the text of the survey is right) must clearly be to some other record preserved in the national treasury. I append about a fifth of the Survey as a specimen of the whole. HOKESLAWE Twywell. Albr[icus] camerar[ius] ii. hidas de feudo Abbatis de Thorneya. Ibidem de feudo Comitis David. Ibidem de feudo Abbatis Burgi i. magnam virgatam. In Slipton i. hidam et unam virgatam de feudo Will'i de Corcy. Ibidem Ricardus filius Hugonis ii. partes unius hidæ de feudo Burgi. Ibidem Rogerus nepos Abbatis tertiam partem unius hidæ de eodem feudo. In Suburc [Sudboro'] ii. hidas [et] dim. de feudo Westmonaster'. In Lofwyc [Luffwick] Th----[1] i. hidam et unam virgatam de feudo de Deneford. Ibidem Radulfus Fleming i. virgatam et dim. de feudo Comitis David. Ibidem Wydo frater ejus i. magnam virgatam de feudo de Thorneya. In Drayton Albr[icus] camerar[ius] dimidiam hidam de feudo R[egis]. In Yslep [Islip] idem Albri[cus] de feudo Regis. Ibidem iiii^{or.} sokemanni Regis i. hidam de feudo Westmonaster'. In Audewyncle [Aldwinkle] Abbas de Burgo iiii. hidas [et] dimidiam quas Ascelinus de Waterville tenet. Ibidem Galfridus de Glynton i. magnam virgatam de feudo Glovernie pertinens ad Barton. Ibidem Ricardus filius Wydonis iii. hidas dim. virg. minus de feudo Regine [_sic_]. Item in Benifeld [Benefield] Willelmus le Lisurs iii. magnas virg. de feudo Regis. In Bernewelle [Barnwell] Robertus de ferariis vi. hidas et i. magnam virg. de feudo Regis. Ibidem Reginaldus le Moyne vi. hidas de feudo de Rammeseye. In Lilleford Willelmus Olyfart v. hidas de feudo Regis Scotie. NAUEFORD In Tytheni [? Tichmarsh] Robertus de Ferr[ers] x. hid. Ibidem Ascelinus de Waterville iii. hid. et i. virg. et tres partes dim. hid. de Burgo.