John Grattan : 



selection, as points between which to measure, those liable to 

 vary from irregularities in the sutures on the vault of the skull. 

 Thus in taking the height he did not choose the spot where the 

 frontal and the two parietal bones join, but one on the vault 6o° 

 from the nasion. His preference for definite angular intervals is 

 again shown by the fact that he took the length and breadth of 

 the cranium at a horizontal plane passing anteriorly io° and 

 posteriorly 150 from the nasio-auditory plane as zero. He found 

 such a section usually intersected the cranium at its longest and 

 broadest diameters. 



The capacity of the cavity of the cranium is obviously of im- 

 portance as an index of the size of the brain, but the determination 

 of its amount is subject to various fallacies. The cavity is filled 

 with some material made up of small solid particles, and the 

 quantity needed for this purpose is then measured. Many of the 

 earlier estimates of cranial capacities are very inaccurate owing to 

 the use of unsuitable substance and the absence of proper pre- 

 cautions when filling the cranial cavity and the measures. Grattan's 

 remarks on this subject show the care and thoroughness with which 

 he pursued his investigations. Thus, he states that he tried sand, 

 sago, and mustard seed, but they all gave unsatisfactory results, 

 since none of these indicated the same capacity when the same 

 experiment was repeated. He found, however, that small round 

 shot gave reliable results, and it is interesting to note that this is 

 the material now generally used. Davis & Thurnam, in the first 

 part of their great work, entitled Crania Britannica, published in 

 1856, state that they employed sand. Grattan refers to this fact, 

 and expresses his regret that they did not use a more reliable 

 material. 



In addition to devising instruments and methods for taking 

 skull measurements he employed them in the study of numerous 

 Irish skulls. Thus, in the Ulster Journal of Archaotogy, Vol. i., 

 j 853, he had a "Notice of an Ancient Sepulchural Mound." 

 From this Mound which was apparently a pre-christian burial 

 place, he obtained 8 skulls sufficiently well preserved to admit of 

 satisfactory measurements. These specimens were probably all 





