A Riddle in Bronze

I too saw the funny side, and moments later we were both shaking with mirth. If one could banish ghosts with happiness alone, at that moment the entire city would have been cleansed of their foul presence. Unfortunately, the power of laughter wouldn't suffice, and so we returned to our work. The mood was noticeably lighter though, and I had a spring in my step as I helped to set up the equipment.
The procedure was similar to that used when banishing the professor's unwanted passenger, and once the net was in position and the lantern — or rather, trap — was installed near the centre of the room, Roberta took out the same tool she'd used on her father. I watched, curious, because unlike earlier, this time there was no knowing where the spirit might be hiding. So how, then, was she going to trap it?
Roberta donned the curious spectacles with their mismatched lenses, and, standing with her back to the door, she traversed the room with an unblinking gaze. Once or twice she paused, seeming to study a piece of furniture, and each time I held my breath. Would the spirit launch from hiding, intent on causing as much harm as possible before it was caught? Or would it slide from one hiding place to the next, trying not to reveal itself?
The tension was unbearable, and I almost prayed for the phantasm to break cover. It would mean facing genuine danger, but anything would be better than this silent anticipation.
"There," murmured Roberta, her voice all but inaudible.
She'd frozen where she stood, and appeared to be looking at the nightstand on the far side of the large bed, where a pitcher of water sat next to an enamelled mug and a silver-backed hand mirror. I stared at the same location, and I fancied I saw a faint shimmering in the air. I could have been imagining things, but even so I felt my hackles rising.
Roberta took a step forward, holding the tool in front of her in the manner of St George approaching the fabled dragon. Then she took another step, and my eyes felt like they were standing proud from my head as I strove to identify the focus of her attention. My hands were clenched, my breathing shallow, and at that moment I had little doubt that the slightest unexpected noise would have stilled the heart pounding in my chest.
Seemingly immune to such fancies, Roberta continued to advance on the nightstand, skirting the bed with the tool held in both hands. There was a faint keening noise, as if the wind were suddenly blowing through a gap in the windows, and it grew louder the closer Roberta got.
Crash!
The nightstand shook from a sudden impact, and the jug sitting on the polished wooden surface toppled to the floor, where it shattered into a dozen pieces. Water sprayed out, hitting the curtains and splashing on the bedspread, and for a brief moment I fancied I saw the outline of a figure inside the welter of flying droplets. Then it was gone, and I saw Roberta leap backwards, brandishing the tool as though warding off an invisible attacker. The end gleamed a dull red, and in the baleful illumination I saw a shadow pursuing her.
"What should I do?" I cried desperately.
"Stay back," she commanded me. "Stay back, and do not approach."
I noticed Roberta was retreating towards the trap in the middle of the bedroom, and as she got closer the keening wail got louder and louder, until I was forced to cover my ears. The window panes shook, rattled by an invisible hand, and then, without warning, a lightning bolt flashed around the room, leaping from one patterned disc to the next. Through half-closed eyes I saw an other-worldly being framed in the circular flash of light, a figure in a tattered nightdress with outstretched arms, its hands like grasping claws.
Then the light winked out, leaving the room in comparative darkness. All I could see was the glow of the tool in Roberta's hand, and a vivid after-image of the lightning flash. Slowly, my eyes began to adjust, and that's when I saw the fine copper netting bulging in the centre. It was as though a heavy body were pushing against the net, and I could see the tripods leaning as they took up the strain.
Roberta was turning her head this way and that, trying to find the spirit, and she hadn't noticed the distorted net. Gritting my teeth, I darted forwards and gripped the net in both hands, right at the bulge, and I started to push against it with all my might.
"What are you doing?" shouted Roberta. "Mr Jones, no! Don't touch that!"
Too late. I felt a chill run up my arms, as though they'd been doused in freezing water. As the cold reached my chest I found I could not breathe, and as my vision dimmed I felt a rising panic. Frantically, I waved at the air in front of me, trying to ward off my unseen assailant, but I was fighting fog and my wild swinging hands achieved nothing.
Roberta was not idle while I struggled. She leapt towards me, brandishing the tool, and the closer she got the more the tip glowed. I was suffering from tunnel vision now, and could barely feel my arms, but I was all too aware of the furnace-like heat emanating from that device in her hands. I felt the spirit release me all of a sudden, and then the net parted in two with a ripping, rending noise.
Roberta cried out in alarm, and she was past me and heading for the bedroom door before I knew what was happening. She stood there with the glowing device held high, and I realised she was trying to herd the spirit back into the centre of the room.
I turned wildly, looking around for any hint of the phantasm, fearing it might assail me from any direction without the slightest warning. Each time I turned