523 
of Edinburgh, Session 1868-69. 
merely tendinous, hitherto fancied to he “the ductus arteriosus,” 
which has really no existence) between its own trunk and that of 
the right pulmonary artery, forming the arch of the aorta, it con- 
tinues its course by the left embryonic ascending aorta (as soon 
as the first inflation of the lung-cells permits the flow of blood from 
the ventricles by their new outlet). The now arterialised blood 
flows down the thoracic and abdominal aorta to be distributed 
through the system. 
The following Gentleman was elected a Fellow of the 
Society : — 
J. Wilson Johnston, M.D., Bengal. 
Monday , 19 th April 1869. 
Professor KELLAND, Vice-President, in the Chair. 
The following Communications were read : — 
1. The Mean Pressure of the Atmosphere, and the Prevail- 
ing Winds for the Months and for the Year. Part II. 
By Alexander Buchan, Secretary of the Meteorological 
Society. 
In Part I., read 16th March 1868, in which was discussed the 
Mean Pressure of the Atmosphere over the Globe for July, 
January, and the year, the method by which the Isobaric Charts 
were constructed was detailed at length. Since March 1868, valu- 
able additional information has been obtained from Australia, New 
Zealand, Tasmania, Africa, South America, the west coast of North 
America, Iceland, and from a few isolated stations in Europe and 
Asia. The period for the British Islands has been extended so as 
to include the eleven years from 1857 to 1867. 
Part II. gives the complete set of Charts for the twelve months 
and for the year. In this Part the prevailing winds were shown from 
good averages collected or calculated for upwards of two hundred 
places over the globe. The general result is that the surface winds 
of the globe flow round and inwards upon regions of low pressure 
