Abstract
FOR the past four years a very simple form of tide-predicting machine, the invention of Captain A. Inglis, the harbour-master, has been in use at Port Adelaide for the construction of the yearly published tide tables. The tides at Port Adelaide are rather peculiar in their behaviour, this being due principally to the fact that the solar and lunar semi-diurnal components are almost exactly equal. At and near the neaps these neutralise one another, and the diurnal components, which are relatively large, are then the main sources of the tidal movement. Before these tides were harmonically analysed, their prediction by ordinary methods was quite impossible, except near the springs. By means of this machine, however, they are now predicted yearly with considerable accuracy. The essential principles of the machine are as follows:—A number of thin wooden templets are cut, each in the form of a sine curve, representing the various tidal components (Fig. 1). These waves are of different lengths, the length of each component wave bearing the same ratio to the solar semi-diurnal as its angular speed does to 15°. The templets are all fixed side by side, with their planes vertical and parallel, being supported on a carrier, which can be moved forward in the direction of the waves by means of a rack and pinion underneath. A number of vertical plungers rest in a transverse line with their lower ends resting on the tops of these templets, and are moved up and down as the curves progress forward. The motions of the plungers are then compounded by means of a fine wire passing over pulleys at the top of each one, and under fixed pulleys between adjacent ones. This wire is connected to an indicator, which moves up and down alongside a vertical scale, thus marking the height of the compound wave at any instant.
Similar content being viewed by others
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
CHAPMAN, R. A Simple Form of Tide Predictor. Nature 68, 322 (1903). https://doi.org/10.1038/068322a0
Issue Date:
DOI: https://doi.org/10.1038/068322a0
This article is cited by
-
Analogue computing with metamaterials
Nature Reviews Materials (2020)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.