Order Heard the parties and perused lower court records. In respect of agreement No. 5 F. 2 of 1979-80, the contractor raised certain claims, which were referred to sole Arbitrator appointed by First Subordinate Judge, Chaibasa, on 5.12.1990. It was related to work known as construction of high level bridge over "Kur. Patta Nala", for which the said agreement was executed. The Arbitrator gave non-speaking award on 19.4.1999 and directed payment of lump sum amount of Rs. 5,06,767/- to the contractor after adjusting the amount already paid to him during progress of work. Rs. 5,19,942/- by way of interest @ 15% per annum was granted on the principal award amount from 30.11.1982 to 3.10.1989 (the period prior to coming to court) and Rs. 8,72,652.00 from 4.10.1989 to 28.3.1999 (pendente lite). A sum of Rs. 58,700/- was awarded as cost of arbitration (detailed in a separate sheet enclosed). Thus total amount of Rs. 19,58,061.00 was directed to be paid to the contractor. 2. On 4.6.1999, the State of Bihar filed objection to the award and prayed to set aside the same, which was registered as Misc. Case No. 4 of 1999. It appears that objector failed to give specific particulars about misconduct, if any, on the part of arbitrator. It was also not proved that he had acted beyond the terms of reference. The award, being non speaking one, the jurisdiction of Court was limited. 3. The Arbitrator was not obliged to give reasons unless there was such stipulation in the agreement itself. It is not open to the court to probe the mental process of the arbitrator and speculate where no reasons is given by him as to what impelled him to arrive at his conclusion. Lump sum award is not bad per se, as such. The Award cannot be said to be invalid merely because it is unreasoned. So the impugned award of principal amount of Rs. 5,19,942.00 cannot be interfered with. The court below rightly made it Rule of Court. 4. Mr. Lump sum award is not bad per se, as such. The Award cannot be said to be invalid merely because it is unreasoned. So the impugned award of principal amount of Rs. 5,19,942.00 cannot be interfered with. The court below rightly made it Rule of Court. 4. Mr. B.B. Sinha, Government Advocate on behalf of appellants submitted that in the agreement there was no express or implied contract for payment of interest and so interest, if any, could have been granted only under section 34 of the Code of Civil Procedure read with section 3 of the Arbitration Act, 1940, and in the present case no interest for preference period should have been granted as the contractor himself was responsible for delay. 5. Mr. V. Shivnath, counsel for respondent, on the other hand, submitted that in the present case State Government was guilty of unreasonable delay, and so arbitrator rightly awarded interest @ 15% per annum for both pre-reference and pendente lite period. 6. I find that arbitrator had not considered the fact that the Contractor in his letter dated 3.9.1983 expressed his inability to complete the work and requested to get measurement done and payment made accordingly. Final measurement was done on 17.1.1984 and the Contractor was asked to accept the same but thereafter he kept silence for about four years and only on 26.8.1988 sent a letter to the Executive Engineer, Road Construction Division, Manoharpur, though his lawyer for arbitration. So, in my opinion, the State Government was not guilty of unreasonable delay. Hence, rate of interest is reduced from 15% to 9% per annum, which, in my opinion, is just and proper and will meet ends of justice in the present cases and is payable only from 26.8.1988 to 19.4.1999 and thereafter interest is payable @ 12% per annum from the date of award till payment. 7. With aforesaid modification in the impugned judgment and award, this appeal is disposed of.