The Accuracy of Tide-predicting Machines

Abstract

IN the article in NATURE for November 24 last appearing under the title “British Research on Tides” there occurs a statement which may, perhaps, leave an erroneous impression with those not familiar with tide-predicting machines. The statement in question—“a test of the accuracy of the tide-predicting machines used by the Admiralty and the India Office has indicated some serious errors in their results, and it is concluded that the labour of reading the curves afforded by the machines, with any pretence to accuracy, is comparable with the labour of direct computation, while the value of the results is greater in the latter case”—although made definitely with reference to particular tide-predicting machines, might, nevertheless, leave the impression that tide-predicting machines in general were subject to “serious errors in their results.” It therefore appears of value to discuss briefly the subject of the accuracy of tide-predicting machines and to refer to some tests made with a direct-reading type of tide predictor.