PROJECTED "KNOCKLAYD" EXPERIMENT 15 



distinguished students at Queen's College. He entered the Indian Civil 

 Service in 1861 and retired in 1889. 



There is a good story told of how Tait saved valuable personal property 

 of his colleague Wyville Thomson from the process of arrestment executed 

 upon the landlord's house and goods. When the bailiffs took possession 

 Tait came on the scene and after some conversation got permission for Wyville 

 Thomson and his wife, who were simply lodgers, to fill two boxes with their 

 purely personal goods. The men of law retired to the kitchen to be refreshed 

 for their labours. They looked out occasionally and always saw the two boxes 

 in the hall being filled. But they did not realise that as soon as one box 

 was filled another took its place, a process of substitution which continued 

 for some little time. Meanwhile the landlord's family thought they might 

 be doing similar deeds of saving, and began to pitch things out of the 

 window. A feather bed happened to fall on an onlooker. The consequent 

 excitement roused the bailiffs from their ease, but not until all the valuables 

 of the Thomsons had been removed. 



Although Tait was professor of pure mathematics in Queen's College, 

 his real interest lay towards the physical side. Writing to his uncle, John 

 Ronaldson, in 1858 he says: 



" I have got the contoured map of Knocklayd from the Ordnance Office and 

 have done a rough calculation which shows io"'28 as the effect on the plumb line, 

 a very hopeful indication. If Thomson reports as well of the geology we shall 

 commence in earnest next summer." 



Knocklayd is a conspicuous hill of conical form in County Antrim, and 

 evidently Tait contemplated using it after the manner of the Schiehallion 

 Experiment to measure the mass of the earth. In one of his quarto note 

 books there are tabulations of stars convenient for zenith observations which 

 he purposed making with suitable instruments both at Belfast and at Knocklayd. 

 Beyond these preparations, nothing more definite seems to have been done. 

 Other problems had to be dealt with and the proposed book on Quaternions 

 pushed on ; and before two more summers had passed Tait had bidden 

 farewell to Ireland and had begun his great career in Edinburgh. 



