Passing now from the witnesses to the subject-matter of the charter, we have first the clause replacing Geoffrey in the same position as he was before the battle of Lincoln, in despite of his treason to the king's cause. The next clause illustrates the system of advancing bids. Whereas the Empress had granted Geoffrey £100 a year, charged on certain manors of royal demesne in Essex, Stephen now increased that grant to £300 a year, by adding the manors of Writtle (£120) and Hatfield (£80). He further granted him another £100 a year payable from lands which had escheated to the Crown. And lastly, he granted to his son Ernulf £100 a year, likewise charged on land. The next clause grants him, precisely as in the charter of the Empress, the constableship of the Tower of London and of its appendant "castle,"[475] with the exception that the Empress uses the term "concedo" where Stephen has "dedi et concessi." The latter expression is somewhat strange in view of the fact that Geoffrey had been in full possession of the Tower before the struggle had begun, and, indeed, by hereditary right. We then return to what I have termed the system of advancing bids. For where the Empress had granted Geoffrey the office of justice and sheriff of Essex alone, Stephen makes him justice and sheriff, not merely of Essex, but of Herts and of London and Middlesex to boot. Nor is even this all; for, whereas the Empress had allowed him to hold Essex to farm for the same annual sum which it had paid at her father's death,[476] Stephen now leases it to him at the annual rent which his grandfather had paid.[477] The fact that in the second charter of the Empress she adopts, we shall find, the original rental,[478] instead of, as before, that which was paid at the time of her father's death, proves that, in this Canterbury charter, Stephen had outbid her, and further proves that Henry I. had increased, after his wont, the sum at which the sheriff held Essex of the Crown. This, indeed, is clear from the Pipe-Roll of 1130, which records a _firma_ far in excess of the £300 which, according to these charters, Geoffrey's grandfather had paid.[479] It may be noted that while Stephen's charter gives in actual figures the "ferm" which had been paid by Geoffrey's grandfather, and which Geoffrey himself was now to pay for London and Middlesex, it merely provides, in the case of Essex and Hertfordshire, that he was to pay what his grandfather had paid, without mentioning what that sum was. Happily, we obtain the information in the subsequent charter of the Empress, and we are tempted to infer from the silence of this earlier charter on the point, that while the ancient _firma_ of London and Middlesex was a sum familiar to men, that of Essex and Herts could only be ascertained by research, pending which the Crown declined to commit itself to the sum.