“ Conceding that the sections are parts of a taxing scheme, and assuming that they are intended to recognize and fully respect the constitutional immunity of a state agency, such as a county, from federal taxation, we think they neither require such transportation to be regarded as a service to the county nor operate to exempt such transportation from the tax.
The tax is not laid on the sale nor because of the sale. It is laid on the transportation and is measured by the transportation charges. ”

“ The Court of Claims, evidently entertaining this view of the exemption, inquires whether the transportation described in the question is a service rendered to the county within the meaning of those sections. The transportation is had at the vendor's instance and is his means of getting his lumber to the place of sale and delivery. ”

“ There are two reasons why a certification by that court which embraces the whole case cannot be entertained by this Court. One is that to accept such a certification and proceed to a determination thereon, in advance of a decision by that Court, would be an exercise of original jurisdiction by this Court contrary to the constitutional provision which prescribes that its jurisdiction shall be appellate in all cases other than those affecting ambassadors, other public ministers and consuls, and those in which a State shall be a party. ”