“The author commences with some remarks on the degree of accuracy attainable by portable magnetic apparatus, and particularly by the use of dipping needles of moderate dimensions. A six-inch needle by Robinson of London, belonging to the Society, together with the Hansteen apparatus for horizontal intensity, were the chief instruments employed by him in a tour through Germany in 1837, in which (though magnetic investigations did not form his primary object), he endeavoured to obtain the approximate value of the elements of dip and intensity for several important stations, and also to carry out into the Eastern Alps the investigations he had already, in 1832, conducted in Switzerland.