The salinity and temperature of the Irish Channel and the waters south of Ireland / by Donald J. Matthews.

  • Matthews, Donald John, 1873-1956.
Date:
1914
Catalogue details

Licence: In copyright

Credit: The salinity and temperature of the Irish Channel and the waters south of Ireland / by Donald J. Matthews. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    o! salt by weight, that is, the number of grammes of total solids contained in a thousand grammes of water, and is calculated from the chlorine content by the formula S=0 03-)-1-8050 Cl. Method of Calculating the Mean Values. Almost the whole of the observations during the quarterly cruises are vertical series, and those from the surface only are so few that they have been disregarded. In order, as I am informed by the officer responsible, to avoid giving a specious appearance of identity to Stations which, owing to weather and other circumstances, were not in fact exactly identical in position, the Irish observing Stations have received a serial number only. For purposes of tabulation the following procedure has therefore been adopted. A chart was prepared for each of the four months, on which were plotted in their correct position all the serial numbers from the beginning for the month in question. It was seen that though the observations tended to fall into groups, yet the area of these groups varied considerably, and some observations were completely isolated. In one or two instances the stations for a cruise had been so placed that they fell midway between the groups formed by the majority ; in this case a section was drawn for these observations and from this was interpolated the most probable value at the centre of each group ; such values were then used as if they had been actually observed. Of course such a method is open to objection, but it is the only one possible short of neglecting the observations entirely, which would probably have given rise to even greater errors. The charts were then carefully examined and pencil lines were drawn to include all positions which fell sufficiently closely to- gether, the size of the group being varied according to the position ; in the North Channel, for instance, the group would have to be very much smaller than in the area close to the south-east coast if the probable error is to be the same in each case. The mean date, position, depth, and temperature and salinity for various strata were then calculated for each of these groups, by interpolation from a curve when observations at a selected depth were missing. In the rather numerous cases where the sprungschict or surface of separation between two bodies of water of different temperature and salinity fell near the missing observation the interpolation is of course extremely uncertain, and to avoid error due to any preconceived idea as to its shape the curve has been drawn here as a straight line. To calculate the mean conditions for the whole year a number was given to each of these groups, and these numbers were plotted again on a fifth chart. Another series of groups was thus obtained, and a final number was given to them when they contained at least two years’ observations for each of the