I had a look back at the Ernest Walker Marwick notes we had looked at before and the full extract reads:
"How would you like to sit in a dark barn, with all the doors open, when all the bogles are around, winnowing with an empty sieve on which you placed a knife, and knowing that an apparition having the appearance of your future partner would pass the door?"
'Winnowing' means to sift or sort the wheat from the chaff and I wonder if shaking the sieve around with a reflective blade on the top was meant to bounce any moonlight that made its way through the open bar door, thus producing a fleeting 'apparition'?
I found another reference to a sieve in the same record in an extract discussing old fashioned medical treatments:
|Orkney Archive Reference D31/72/1/22|