The Sword of Gryffindor

[Jayne]

No: HPFGUIDX 182563

Just going back to the original question re Sword. I have another one 
to ask. How exactly did Snape get the sword into the lake for Harry to 
see it. Surely he would have been seen if he had appeared there and put 
it in ?
Could the Silver Doe have some how got it there.
 Also how did he know that Harry would find it. No one knew where they 
were hiding ?

Jayne confused again