Specific passage: 

"Time crept by—seven minutes seemed endless. Only two and a half had passed when he looked at his watch again, worried that he might have missed the precise moment. He did a thousand things, picked up objects, put them back down, walked out onto the balcony, but not so that his cousin could notice, looked at the landscape of this Alpine valley, his eyes now more than familiar with its shapes and forms—its peaks, ridges, and cliffs; in the background on his left, though somewhat closer, was the jutting Brämenbühl, whose crest fell abruptly toward town and whose flank was thickly covered with coarse grasses; there were the mountain formations on his right, whose names he also knew by now; and then to the south was the Alteinwand, which from here looked as if it closed off the valley. He looked down at the paths and flowerbeds of the level gardens, the grotto, the silver fir, listened to whispers drifting up from the lounging area, where people were taking their rest cure—and turned back into the room, where he tried to correct the way the instrument sat in his mouth. Stretching his arm to free his wrist from its sleeve, he brought his forearm up to his eyes. With much trouble and effort—as if he were shoving, pushing, kicking them—he had got rid of six minutes. But now, standing there in the middle of the room, he fell to daydreaming and let his thoughts wander, and the one remaining minute scurried away on little cat’s feet, until another motion of his arm told him that the minute had secretly escaped and that it was a little late now. Almost a third of the next had passed before he grabbed the thermometer from his mouth, telling himself that it did not really matter, would not alter the results, could not hurt anything—and he stared down at it now with confusion in his eyes." - Thomas Mann The Magic Mountain

Close reading:

Nearing the end of the fourth chapter, Hans Castorp suspected that he caught a cold, and was looking to verify this. This passage describes him taking his temperature, and realizing that he does in fact have a fever. Ultimately, this section can be read as an encapsulation of the novel’s motif of a moment, or an eternity, stuck in time. 

We first are introduced to this motif when Castorp arrives at the sanatorium. Upon meeting his cousin, and telling him that he only plans on staying for three weeks, his cousin replies that, up there, “three weeks are the same as a day”. This theme is constantly present up to this point, being especially recently refreshed in the section “Excursus on the Sense of Time”, where Castorp ruminates for an entire night about how time can be lengthened or shortened, either in the present or upon recollection, depending on the events taking place. The theme repeated throughout this entire first section of the novel is that time flows separately in the sanatorium -- most of the patients have no direct control over their progress, and so have no need for the concept of time. 

So when Castorp begins to suspect that he may be sick, that he may be stuck in the sanatorium for an unknown period of time, his perception of time shifts accordingly. He experiences, in these seven minutes of waiting, a year’s worth of activity in the institution. He does “a thousand things”, nominally to pass the time, but it effects no change. The objects that he picks up, he puts back down. He is acclimated to his surroundings -- not the mountains, exactly, but the frame of mind of the people around him. Certainly, though, he is familiar with the landscape, as one would be with one’s home. He describes only the mountains, the territory claimed by the sanatorium. They are the context with which he places everything else. The town is only described as being on the foot of Brämenbühl. Alteinwand, on the other side, fences off the rest of the world from the little sanctuary. The Alps here serve as a border, cutting him off from what is down there. As if in preparation for weeks feeling like days, he ascends every peak, ridge, and cliff in six minutes. And finally, despite Castorp fretting over the exactness of the seven minutes, he still loses track of time. He isn’t a second too quick or a second too slow, but a full third of a minute past his mark. His temperature by this point is a formality. He has already succumbed to the sick state of mind as would be described by Settembrini. We know, by now, that he belongs in the sanctuary.

The form in which Mann writes the wait adds an extra element of restlessness. The sentences describing his actions to pass the time are long and flowing, as if Castorp’s thoughts flow directly from object to object, peak to peak. There is no paragraph break for the entirety of this section. He is frantic, almost, to have an answer, to receive a verdict. But, like the other patients, he comes to terms with his condition. He is tired out after wasting away six of the seven minutes, and can do nothing but daydream, that activity which is most associated with time lost for naught. And there, finally, he loses his temporal sense.