SATYANARAYANA RAO, J.

This revision petition under Section 12B of the Madras General Sales Tax Act raises an important question regarding the constitutional validity of certain of the provisions of the Madras General Sales Tax Amendment Act (XXV of 1947) by which "works contracts" were included within the ambit of the Madras General Sales Tax Act and they are made subject to the levy of sales tax within the limitations provided in the said Act. The case was argued with considerable ability on both sides and all the available authorities bearing on the question, which the industry of counsel could discover, were placed before us.

The assessees, Messrs. Gannon Dunkerley & Co. (Madras) Ltd., are a private limited company incorporated under the Indian Companies Act and they carry on business as engineers and contractors. The head office of the company is at Madras but their work-spots are spared over several places in Sough India. Their business consists mainly of execution of contracts for construction of buildings, bridges, dams, roads and structural contracts of all kinds. The important customers of the company are the Central and State Governments but there are also some