Harold was most intrigued to see what Sid had set up, and while part of him had preferred a student take up the mantle, he had to admit some of those present were not... entirely prepared. And he supposed that it rather suited for a sceptic to go first, partially to demonstrate that it was safe and partially to demonstrate that, well, the results were educated guesswork at best.
He pushed his glasses back on the bridge of his nose, watching curiously as Sid poured the contents of a small drawstring bag into a rough approximation of a circle. There was an almost involuntary gasp; the content was fine, white powdery sand - with a sheen that fine, it could only be the kind of sand for the finest of hourglasses: time sand. It had some rather fascinating arcanochrometic properties and was... frankly, exceedingly rare! Far too rare for pouring on the floor - unless Sid had some other source that he, Harold, wasn't aware of. The man had travelled widely, as far as he could tell, and it was entirely possible he knew somewhere out in the wider world where sand wasn't quite so precious a resource.
After what he thought was a shade theatrical, Harold watched with fascination as Sid sat back down and looked into his eyes. Harold tried to hide his internal scepticism but it ran rather deep - especially considering his time in the Time Room and what he had learned, discovered and taught in there.
Sure enough, the theatricality ran deeply as Sid ignited the fire with his wand, the sands of time burned with a shade of blue Harold had always admired, and before he knew it, Sid was reaching for his hand. Harold offered it freely - whatever connection there was to be made, touch always made it stronger. That was magic he'd always known.
Harold could only look on as Sid fell into what must have been a sort of trance, as to Harold's shock, his friend's eyes turned completely white. That was something he'd not seen before, the look of a sight beyond sight. But if he was shocked by the appearance of that, it paled into a faded muted stillness as he began to hear words coming out of Sid's mouth.
Words that had a meaning Sid could not possibly know, let alone fathom, and came with an intonation that was not his normal voice. It was deeper, richer, more vibrant.
As each new statement came forth, Harold's reaction mixed from bemusement to concern to confusion, through the gamut of feelings simply because it was precisely the sort of message he would hear from the likes of his former employer, the Department of Mysteries, with secrets within secrets with riddles wrapped up in enigmas.
The ringmaster falling? Bah, no great surprise - the rumours over the summer had suggested as much as had his own digging on the matter - yet he had said nothing to anyone inside the castle except Albus, and Albus would have no reason to share this with Sid.
The target girl? Sylvia perhaps? Going forward to find her fate was the original excuse given for where he thought she'd disappeared to, after all. Joining with the lion tamer, though, that fitted in with his latter learnings, on the notion of the errant element within the Ministry and who they might be working for. The blonde mane and scar, though, that threw him - the chap he'd seen earlier in the summer on the day he'd visited, he didn't recognise him, but in a department where everyone had to actively demonstrate an ability to pose as another, it was hardly surprising.
The plan of the inn by the tree near the water... Harold shuddered involuntarily. That moment where someone is described as walking over one's grave. There was no way Sid could know about that, no way, not even as learned as he was.
The thoughts of a changeling and a suspicious apparition were just good practice; one should always rather attempt to catch a changeling if one is able, and all apparitions should be deemed suspicious until proven otherwise. Especially the ones on unfinished business.
The flames around them extinguished, and all that was left were glass shards, as Sid made some mention of seeing the lion tamer's face. Harold reached for a sliver of glass but only saw his own face in it, distorted by the curvature of the shard.
Sid let go of his hand and the room restored itself around them. Harold could only sit there, mildly stunned in the aftermath, as Sid encouraged a student to give it a go.
The worst part is that Harold was wondering if he was himself applying his own context and meaning to proceedings and that whatever Sid was receiving magically - though, curiously, not telepathically, as Harold would have noticed that - may have meant nothing at all in its own right, or it may have meant everything. He would need to talk to Albus about this, and perhaps Sid too, in due course.
Sid also mentioned leaving the left window open. Harold smiled politely, "Thank you, yes, I'll try to remember that." It was about all he could say, such was the shock of everything else.
After a few moments had passed, though, Harold found himself rather unexpectedly right as rain again. He turned to the students, "Well, that was a rather unexpected experience. I should ponder quite deeply over the things Professor Montgomery has said, I'm sure there will be some meaning in there, even if not quite obvious to the observer. Go on, see what mysteries you might learn."