298. Their parallelism is difficult to be ascertained; for, on account of the magnitude and inaccessibility of the objects, it is impossible to place the eye in any situation, where it shall not be much nearer to one part of the planes whereof the parallelism is to be estimated, than to another. Indeed, one can perceive a cause which may have rendered the parallelism of the plates of granite which compose the _aiguilles_, more accurate in appearance than in reality, when viewed from a point so elevated as the summit of Mont Blanc. For, even on the supposition that the comparison of those plates to leaves of artichokes was just, and that the planes of their separation converged toward one another, in ascending to the top, when they were viewed from a point more elevated than that top, this convergency would be diminished, and, by the force of the perspective, might even be converted into parallelism. We cannot at present ascertain what effect this cause of deception may have actually produced. 299. The observations of Saussure concerning the stratification of granite, are not, however, in all instances, liable to these objections; and it seems to be on much less exceptionable grounds that he pronounces the granite of St Gothard to be stratified. The gneiss and micaceous schistus which constitute the lower part of that mountain, are succeeded by a granite without any schistose appearance, but divided into large plates, exactly parallel to the beds of the former gneiss. These he regards as real strata. On studying them in detail, he says, considerable irregularities were to be observed, but not greater than in the case of limestone or micaceous schistus.[153] It may be inferred from this, that these plates of granite are not so thick but that they admit of comparison with beds that are known with certainty to be of aqueous formation, and I am therefore disposed to believe, that the granite of St Gothard, in this part at least, is stratified. The transition from gneiss to granite en masse, is not uncommon, as Saussure has observed in other instances, and as we are just about to consider more particularly. [Footnote 153: Voyages aux Alpes, tom. iv. § 1830.]